msg beep

Oh yeah and be sure to include using System.Runtime.InteropServices;

Decorate the function with an DllImport Attribute use the extern a static key words. You can look up API descriptions here : ms-help://MS.VSCC/MS.MSDNVS/win32/win32start_1xyd.htm [DllImport("Kernel32.dll", EntryPoint="Beep")] private static extern bool MyBeep(int dwFreq, int dwDuration); private void button5_Click(object sender, System.EventArgs e) { MyBeep(500,125); }