When i launched NUnit test cases from NAnt the test cases are executed and the console did not return back and NAnt script was executing continuously. Then I tried it by running NUnit console same problem occur the console NUnit console was not returning after executing the tests. Then I tried running by NUnit-Console-X86 file it returned successfully after executing it. Please solve the problem with NUnit 64 bit version. As some of my test case needs 64 bit runner.