Use the namespace using System.Runtime.InteropServices; Then use DllImport " DllImportAttribute Class Indicates that the attributed method is exposed by an unmanaged dynamic-link library (DLL) as a static entry point." Use the lines below [ DllImport ( "user32.dll" , CharSet = CharSet .Unicode)] public static extern int MessageBox( IntPtr hWnd, String Text, String Caption, uint type); InPtr This type implements the ISerializable interface. And then put this code MessageBox( new IntPtr (0), "Hello World" , "Hello Dialog name" , 0); Note: The DllImportAttribute does not support marshaling of generic types.