Does recompilation needed from framework 2.0 to framework 3.5

 I have an old Web application which is using net framework 2.0(build with vs2005),  now i need to move the old Web application to production server which has  .net framwork 3.5 installed. Do I need recompile  the web application with vs2008 or i can just go head move the the Web application without recompiling, it will automatically work?
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