Ron, the casino should be able to provide that information IF you use a player's card everytime you play. I don't know about machine serial numbers being stored as part of the information tracked by the computers for play using the card during every bet in a machine, but the info that is tracked should be sufficient to prove net winnings or losses. If your friend was using a player's card, the casino can provide a written history of wins and losses for tax reporting purposes. The player's cards can come in handy for way more than casino comps. If he wasn't using a card in the machines, there is no record of losing bets. If he was using the card in the machines and paid $8000 in back taxes on gaming winnings, either he won enough to pay the tax or had an accountant who gave him bad advice.

Bob