diff --git a/refactoring.java/src/org/netbeans/modules/refactoring/java/plugins/RenameRefactoringPlugin.java b/refactoring.java/src/org/netbeans/modules/refactoring/java/plugins/RenameRefactoringPlugin.java
--- a/refactoring.java/src/org/netbeans/modules/refactoring/java/plugins/RenameRefactoringPlugin.java
+++ b/refactoring.java/src/org/netbeans/modules/refactoring/java/plugins/RenameRefactoringPlugin.java
@@ -45,6 +45,8 @@
 import com.sun.source.tree.Tree;
 import com.sun.source.util.TreePath;
 import java.io.IOException;
+import java.net.MalformedURLException;
+import java.net.URL;
 import java.text.MessageFormat;
 import java.util.*;
 import javax.lang.model.element.*;
@@ -52,11 +54,18 @@
 import javax.lang.model.util.ElementFilter;
 import javax.lang.model.util.Elements;
 import org.netbeans.api.java.source.*;
+import org.netbeans.api.project.FileOwnerQuery;
+import org.netbeans.api.project.Project;
+import org.netbeans.api.project.SourceGroup;
+import org.netbeans.api.project.Sources;
 import org.netbeans.modules.refactoring.api.*;
 import org.netbeans.modules.refactoring.java.RetoucheUtils;
 import org.netbeans.modules.refactoring.java.spi.JavaRefactoringPlugin;
 import org.openide.filesystems.FileObject;
 import org.netbeans.modules.refactoring.spi.RefactoringElementsBag;
+import org.netbeans.spi.java.queries.MultipleRootsUnitTestForSourceQueryImplementation;
+import org.openide.filesystems.URLMapper;
+import org.openide.util.Exceptions;
 import org.openide.util.NbBundle;
 import org.openide.util.Utilities;
 
@@ -267,6 +276,15 @@
                 
 //                String fqn = "".equals(pkgname) ? newName : pkgname + '.' + newName;
 //                ClassPath cp = ClassPath.getClassPath(fo, ClassPath.SOURCE);
+                String conflictingSource=checkClassRenameInComplementarySource(primFile,newFqn+newName);
+                if(conflictingSource!=null) {
+                    String msg = new MessageFormat(getString("ERR_ClassClash")).format(
+                            new Object[] {newName, conflictingSource}
+                    );
+                    fastCheckProblem = createProblem(fastCheckProblem, true, msg);
+                    return fastCheckProblem;
+                }
+
                 if (RetoucheUtils.typeExist(treePathHandle, newFqn)) {
                     String msg = new MessageFormat(getString("ERR_ClassClash")).format(
                             new Object[] {newName, pkgname}
@@ -308,7 +326,42 @@
         }
         return fastCheckProblem;
     }
-    
+
+    /**
+     * Check if file rename is ok looking in a complementary source.<br/>
+     * For normal sources it checks the rename in test and form test sources in normal sources
+     * @param oldFile The file to rename
+     * @param newFQNClassName New FQN of the class
+     * @return null if the rename is correct, conflicting path otherwise
+     */
+    private String checkClassRenameInComplementarySource(FileObject oldFile,String newFQNClassName) {
+            Project project=FileOwnerQuery.getOwner(oldFile);
+            Sources sources=project.getLookup().lookup(Sources.class);
+
+            MultipleRootsUnitTestForSourceQueryImplementation mrufqi=project.getLookup().lookup(MultipleRootsUnitTestForSourceQueryImplementation.class);
+            for(SourceGroup sg:sources.getSourceGroups(org.netbeans.api.java.project.JavaProjectConstants.SOURCES_TYPE_JAVA)) {
+                URL urlut[]=mrufqi.findUnitTests(sg.getRootFolder());
+                URL urlso[]=mrufqi.findSources(sg.getRootFolder());
+
+                assert !(urlut!=null && urlso!=null);
+                URL[] urlstolook=urlut!=null?urlut:urlso;
+
+               if(urlstolook!=null) {
+                    for(URL u:urlstolook) {
+                        try {
+                            URL newURL = new URL(u, newFQNClassName.replaceAll("\\.", "/")+"."+oldFile.getExt());
+                            FileObject file=URLMapper.findFileObject(newURL);
+                            if(file!=null)
+                                return file.getParent().getPath();
+                        } catch (MalformedURLException ex) {
+                            Exceptions.printStackTrace(ex);
+                        }
+                    }
+                }
+            }
+            return null;
+    }
+
     @Override
     protected Problem checkParameters(CompilationController info) throws IOException {