How To Get Serial Hard Disk

function GetHardDiskSerial(const DriveLetter: Char): string;
var
 NotUsed:     DWORD;
 VolumeFlags: DWORD;
 VolumeInfo:  array[0..MAX_PATH] of Char;
 VolumeSerialNumber: DWORD;
begin
 GetVolumeInformation(PChar(DriveLetter + ':\'),
   nil, SizeOf(VolumeInfo), @VolumeSerialNumber, NotUsed,
   VolumeFlags, nil, 0);
 Result := Format('Label = %s   VolSer = %8.8X',
   [VolumeInfo, VolumeSerialNumber])
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
 ShowMessage(GetHardDiskSerial('c'));
end;