diff --git a/modules/swagger-codegen/src/main/java/io/swagger/codegen/CodegenParameter.java b/modules/swagger-codegen/src/main/java/io/swagger/codegen/CodegenParameter.java
index 6dd85d10c27..38c70fcc82e 100644
--- a/modules/swagger-codegen/src/main/java/io/swagger/codegen/CodegenParameter.java
+++ b/modules/swagger-codegen/src/main/java/io/swagger/codegen/CodegenParameter.java
@@ -7,7 +7,8 @@ import java.util.List;
 
 public class CodegenParameter {
     public Boolean isFormParam, isQueryParam, isPathParam, isHeaderParam,
-            isCookieParam, isBodyParam, isFile, notFile, hasMore, isContainer, secondaryParam, isBinary;
+            isCookieParam, isBodyParam, isFile, notFile, hasMore, isContainer, 
+            secondaryParam, isBinary, isCollectionFormatMulti;
     public String baseName, paramName, dataType, collectionFormat, description, baseType, defaultValue;
     public String jsonSchema;
     public boolean isEnum;
@@ -33,6 +34,7 @@ public class CodegenParameter {
         output.paramName = this.paramName;
         output.dataType = this.dataType;
         output.collectionFormat = this.collectionFormat;
+        output.isCollectionFormatMulti = this.isCollectionFormatMulti;
         output.description = this.description;
         output.baseType = this.baseType;
         output.isFormParam = this.isFormParam;
diff --git a/modules/swagger-codegen/src/main/java/io/swagger/codegen/DefaultCodegen.java b/modules/swagger-codegen/src/main/java/io/swagger/codegen/DefaultCodegen.java
index 840e646b5d8..575f9742f50 100644
--- a/modules/swagger-codegen/src/main/java/io/swagger/codegen/DefaultCodegen.java
+++ b/modules/swagger-codegen/src/main/java/io/swagger/codegen/DefaultCodegen.java
@@ -1205,6 +1205,9 @@ public class DefaultCodegen {
             p._enum = model._enum;
             p.allowableValues = model.allowableValues;
             p.collectionFormat = collectionFormat;
+            if(collectionFormat != null && collectionFormat.equals("multi")) {
+                p.isCollectionFormatMulti = true;
+            }
             p.paramName = toParamName(qp.getName());
 
             if (model.complexType != null) {
diff --git a/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/JavaClientCodegen.java b/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/JavaClientCodegen.java
index cdcd15f9a5d..d265e5a7232 100644
--- a/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/JavaClientCodegen.java
+++ b/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/JavaClientCodegen.java
@@ -218,6 +218,7 @@ public class JavaClientCodegen extends DefaultCodegen implements CodegenConfig {
             supportingFiles.add(new SupportingFile("build.sbt.mustache", "", "build.sbt"));
         } else if ("retrofit".equals(getLibrary())) {
             supportingFiles.add(new SupportingFile("auth/OAuthOkHttpClient.mustache", authFolder, "OAuthOkHttpClient.java"));
+            supportingFiles.add(new SupportingFile("CollectionFormats.mustache", invokerFolder, "CollectionFormats.java"));
         } else {
             supportingFiles.add(new SupportingFile("TypeRef.mustache", invokerFolder, "TypeRef.java"));
         }
diff --git a/modules/swagger-codegen/src/main/resources/Java/libraries/retrofit/CollectionFormats.mustache b/modules/swagger-codegen/src/main/resources/Java/libraries/retrofit/CollectionFormats.mustache
new file mode 100644
index 00000000000..5e165a2bd53
--- /dev/null
+++ b/modules/swagger-codegen/src/main/resources/Java/libraries/retrofit/CollectionFormats.mustache
@@ -0,0 +1,95 @@
+package {{invokerPackage}};
+
+import java.util.Arrays;
+import java.util.List;
+
+public class CollectionFormats {
+    
+    public static class CSVParams {
+
+        protected List<String> params;
+        
+        public CSVParams() {
+        }
+        
+        public CSVParams(List<String> params) {
+            this.params = params;
+        }
+        
+        public CSVParams(String... params) {
+            this.params = Arrays.asList(params);
+        }
+
+        public List<String> getParams() {
+            return params;
+        }
+
+        public void setParams(List<String> params) {
+            this.params = params;
+        }
+        
+        @Override
+        public String toString() {
+            return String.join(",", params);
+        }
+        
+    }
+    
+    public static class SSVParams extends CSVParams {
+        
+        public SSVParams() {
+        }
+        
+        public SSVParams(List<String> params) {
+            super(params);
+        }
+
+        public SSVParams(String... params) {
+            super(params);
+        }
+
+        @Override
+        public String toString() {
+            return String.join(" ", params);
+        }
+    }
+    
+    public static class TSVParams extends CSVParams {
+        
+        public TSVParams() {
+        }
+        
+        public TSVParams(List<String> params) {
+            super(params);
+        }
+        
+        public TSVParams(String... params) {
+            super(params);
+        }
+
+        @Override
+        public String toString() {
+            return String.join("\t", params);
+        }
+    }
+    
+    public static class PIPESParams extends CSVParams {
+        
+        public PIPESParams() {
+        }
+        
+        public PIPESParams(List<String> params) {
+            super(params);
+        }
+        
+        public PIPESParams(String... params) {
+            super(params);
+        }
+
+        @Override
+        public String toString() {
+            return String.join("|", params);
+        }
+    }
+    
+}
diff --git a/modules/swagger-codegen/src/main/resources/Java/libraries/retrofit/api.mustache b/modules/swagger-codegen/src/main/resources/Java/libraries/retrofit/api.mustache
index b41e18aff47..dc560e64e4d 100644
--- a/modules/swagger-codegen/src/main/resources/Java/libraries/retrofit/api.mustache
+++ b/modules/swagger-codegen/src/main/resources/Java/libraries/retrofit/api.mustache
@@ -1,5 +1,9 @@
 package {{package}};
 
+import {{invokerPackage}}.CollectionFormats.*;
+
+import {{modelPackage}}.*;
+
 import retrofit.Callback;
 import retrofit.http.*;
 import retrofit.mime.*;
diff --git a/modules/swagger-codegen/src/main/resources/Java/libraries/retrofit/queryParams.mustache b/modules/swagger-codegen/src/main/resources/Java/libraries/retrofit/queryParams.mustache
index e0a58533e5f..3c5b1bb7e69 100644
--- a/modules/swagger-codegen/src/main/resources/Java/libraries/retrofit/queryParams.mustache
+++ b/modules/swagger-codegen/src/main/resources/Java/libraries/retrofit/queryParams.mustache
@@ -1 +1 @@
-{{#isQueryParam}}@Query("{{baseName}}") {{{dataType}}} {{paramName}}{{/isQueryParam}}
\ No newline at end of file
+{{#isQueryParam}}@Query("{{baseName}}") {{#collectionFormat}}{{#isCollectionFormatMulti}}{{{dataType}}}{{/isCollectionFormatMulti}}{{^isCollectionFormatMulti}}{{{collectionFormat.toUpperCase}}}Params{{/isCollectionFormatMulti}}{{/collectionFormat}}{{^collectionFormat}}{{{dataType}}}{{/collectionFormat}} {{paramName}}{{/isQueryParam}}
\ No newline at end of file
diff --git a/samples/client/petstore/java/retrofit/src/main/java/io/swagger/client/CollectionFormats.java b/samples/client/petstore/java/retrofit/src/main/java/io/swagger/client/CollectionFormats.java
new file mode 100644
index 00000000000..62126189199
--- /dev/null
+++ b/samples/client/petstore/java/retrofit/src/main/java/io/swagger/client/CollectionFormats.java
@@ -0,0 +1,95 @@
+package io.swagger.client;
+
+import java.util.Arrays;
+import java.util.List;
+
+public class CollectionFormats {
+    
+    public static class CSVParams {
+
+        protected List<String> params;
+        
+        public CSVParams() {
+        }
+        
+        public CSVParams(List<String> params) {
+            this.params = params;
+        }
+        
+        public CSVParams(String... params) {
+            this.params = Arrays.asList(params);
+        }
+
+        public List<String> getParams() {
+            return params;
+        }
+
+        public void setParams(List<String> params) {
+            this.params = params;
+        }
+        
+        @Override
+        public String toString() {
+            return String.join(",", params);
+        }
+        
+    }
+    
+    public static class SSVParams extends CSVParams {
+        
+        public SSVParams() {
+        }
+        
+        public SSVParams(List<String> params) {
+            super(params);
+        }
+
+        public SSVParams(String... params) {
+            super(params);
+        }
+
+        @Override
+        public String toString() {
+            return String.join(" ", params);
+        }
+    }
+    
+    public static class TSVParams extends CSVParams {
+        
+        public TSVParams() {
+        }
+        
+        public TSVParams(List<String> params) {
+            super(params);
+        }
+        
+        public TSVParams(String... params) {
+            super(params);
+        }
+
+        @Override
+        public String toString() {
+            return String.join("\t", params);
+        }
+    }
+    
+    public static class PIPESParams extends CSVParams {
+        
+        public PIPESParams() {
+        }
+        
+        public PIPESParams(List<String> params) {
+            super(params);
+        }
+        
+        public PIPESParams(String... params) {
+            super(params);
+        }
+
+        @Override
+        public String toString() {
+            return String.join("|", params);
+        }
+    }
+    
+}
diff --git a/samples/client/petstore/java/retrofit/src/main/java/io/swagger/client/StringUtil.java b/samples/client/petstore/java/retrofit/src/main/java/io/swagger/client/StringUtil.java
index 27a06a7cfc2..5f09a3edfeb 100644
--- a/samples/client/petstore/java/retrofit/src/main/java/io/swagger/client/StringUtil.java
+++ b/samples/client/petstore/java/retrofit/src/main/java/io/swagger/client/StringUtil.java
@@ -1,6 +1,6 @@
 package io.swagger.client;
 
-@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2015-09-18T14:07:38.326+02:00")
+@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2015-10-11T00:10:38.251+02:00")
 public class StringUtil {
   /**
    * Check if the given array contains the given value (with case-insensitive comparison).
diff --git a/samples/client/petstore/java/retrofit/src/main/java/io/swagger/client/api/PetApi.java b/samples/client/petstore/java/retrofit/src/main/java/io/swagger/client/api/PetApi.java
index f6b29f11a2a..49e1657e0e5 100644
--- a/samples/client/petstore/java/retrofit/src/main/java/io/swagger/client/api/PetApi.java
+++ b/samples/client/petstore/java/retrofit/src/main/java/io/swagger/client/api/PetApi.java
@@ -1,5 +1,9 @@
 package io.swagger.client.api;
 
+import io.swagger.client.CollectionFormats.*;
+
+import io.swagger.client.model.*;
+
 import retrofit.Callback;
 import retrofit.http.*;
 import retrofit.mime.*;
diff --git a/samples/client/petstore/java/retrofit/src/main/java/io/swagger/client/api/StoreApi.java b/samples/client/petstore/java/retrofit/src/main/java/io/swagger/client/api/StoreApi.java
index 16819d04a94..abdf952631b 100644
--- a/samples/client/petstore/java/retrofit/src/main/java/io/swagger/client/api/StoreApi.java
+++ b/samples/client/petstore/java/retrofit/src/main/java/io/swagger/client/api/StoreApi.java
@@ -1,5 +1,9 @@
 package io.swagger.client.api;
 
+import io.swagger.client.CollectionFormats.*;
+
+import io.swagger.client.model.*;
+
 import retrofit.Callback;
 import retrofit.http.*;
 import retrofit.mime.*;
diff --git a/samples/client/petstore/java/retrofit/src/main/java/io/swagger/client/api/UserApi.java b/samples/client/petstore/java/retrofit/src/main/java/io/swagger/client/api/UserApi.java
index a5bc4d03477..f56ad5aabb3 100644
--- a/samples/client/petstore/java/retrofit/src/main/java/io/swagger/client/api/UserApi.java
+++ b/samples/client/petstore/java/retrofit/src/main/java/io/swagger/client/api/UserApi.java
@@ -1,5 +1,9 @@
 package io.swagger.client.api;
 
+import io.swagger.client.CollectionFormats.*;
+
+import io.swagger.client.model.*;
+
 import retrofit.Callback;
 import retrofit.http.*;
 import retrofit.mime.*;