I am trying to use DLLImport for using Win32 dll method in C#. Win32 dll C++ // .h file #ifdef IMPORTDLL_EXPORTS #define IMPORTDLL_API __declspec(dllexport) #else #define IMPORTDLL_API __declspec(dllimport) #endif // This class is exported from the ImportDLL.dll class IMPORTDLL_API CImportDLL { public: CImportDLL(void); // TODO: add your methods here. int Add(int a , int b); }; extern IMPORTDLL_API int nImportDLL; IMPORTDLL_API int fnImportDLL(void); IMPORTDLL_API int fnMultiply(int a,int b); // .cpp file // ImportDLL.cpp : Defines the exported functions for the DLL application. // #include "stdafx.h" #include "ImportDLL.h" // This is an example of an exported variable IMPORTDLL_API int nImportDLL=0; // This is an example of an exported function. IMPORTDLL_API int fnImportDLL(void) { return 42; } IMPORTDLL_API int fnMultiply(int a , int b) { return (a*b); } Once i build this i get ImportDLL.dll Now i create Windows Application and add this dll in debug folder and try to use this method using DLLImport [DllImport("ImportDLL.dll")] public static extern int fnMultiply(int a, int b); And I try to call this in C# int a = fnMultiply(5, 6); // This line gives error Unable to find an entry point Can any body tell what i am missing? Thanks.