var
DCDesk: HDC;
bmp: TBitmap;
begin
bmp := TBitmap.Create;
bmp.Height := Screen.Height;
bmp.Width := Screen.Width;
DCDesk := GetWindowDC(GetDesktopWindow);
BitBlt(bmp.Canvas.Handle, 0, 0, Screen.Width, Screen.Height,
DCDesk, 0, 0, SRCCOPY);
bmp.SaveToFile('ScreenShot.bmp');
ReleaseDC(GetDesktopWindow, DCDesk);
bmp.Free;
end;