See attached. Takes a window handle (returned by WinGetHandle) of the process into which the dll will be injected and a string path to the dll that will be injected. Example: $ret = _InjectDll(WinGetHandle("Calculator"), "c:\testdll.dll") $err = @error If $err < 0 Then MsgBox(16, $ret, $err) Else MsgBox(64, $ret, "YUP!") EndIf_InjectDll.au3