Bates started the final round at the Dakota Dunes Country Club in Dakota Dunes, S.D. with a one-shot lead - a lead he never relinquished on Sunday.
Bates shot a 2-under 70 to finish the tournament at 15-under-par 273, one shot clear of Matt Kuchar (66) and 1988 U.S. Amateur champion Eric Meeks (68).
'This is far and away the greatest day in golf for me,' said Bates, who underwent neck surgery in April of last year.
Kuchar, the 1997 U.S. Amateur champion, was competing in just his third Buy.Com event on the year. By collecting $37,400, Kuchar moves to 55th on the money list.
Bates made $76,500 and now stands in 13th place in earnings.
Bates, who turns 32 this coming Sunday, is in his sixth straight season on the Buy.Com Tour. Coincidentally, he earned his way onto the PGA Tour in 1995, in part, by winning the '94 Siouxland Open.
'When I won here before, that was fantastic,' he said. 'Back then I thought I was going to be a rising star and thought it would be my only year on this tour. Even back in January I was doubting that I could ever play out here and be competitive again. I cried with my wife several times, wondering if I could do it. I just prayed for courage today. I'm very thankful and very humbled to have won today.'
Full-field scores from the Buy.Com Siouxland Open