The largest pay out from a slot machine was $39,713,982.25. It happened at the Excalibur Hotel and Casino on March 21, 2003. The big winner was a 25-year-old software engineer who had put about $100.00 into a progressive Megabucks machine when it hit.
Another payout of note was to Sue Henley in 1997. She won $12,510,549 on April 14 at the New York New York Hotel and Casino. This also came out of a Megabucks slot machine and was the largest slots jackpot in history to date.