procedure TForm1.DBGrid1DrawDataCell(Sender: TObject; const Rect:
TRect; Field: TField; State: TGridDrawState);
var
iRowNumber : Integer;
begin
with (Sender as TDBGrid), Canvas do begin
iRowNumber := (Rect.Top + Rect.Bottom) div ((1+Rect.Bottom - Rect.Top)*2);
if Odd(iRowNumber) then Brush.Color := clYellow
else Brush.Color := clWhite;
FillRect(Rect);
DefaultDrawDataCell(Rect, Field, State);
end;
end;