There has been recent talks about UFC fighters betting on themselves to win a fight, and some that even did it. UFC Fight Night: Justin Jaynes bets on himself vs. Charles Rosa (yahoo.com) Here's a law review article on potential criminal penalties: Criminalizing Match-Fixing as America Legalizes Sports Gambling (marquette.edu) The more interesting situation is what happens if a UFC fighter bets on their opponent to win. I do not see any obvious rules/regulation that would prevent this. There seems to be laws that forbid the bribing of persons to influence the outcome of a sporting event, but there doesn't seem to be any sort of criminal penalties in place that would prevent an UFC fighter from betting on his opponent. The UFC does have a code of conduct but that doesn't specifically address any situation where a fighter would bet on their opponent (arguably it's conduct that can hurt the reputation of the company, but that's very vague, and applies to so many things). I think in this hypothetical, you can get away with it. Let's say Fighter A, decides to bet on Fighter B to win the fight by decision. If confronted and asked Fighter A why did they did; and the reasoning was, Fighter A did not try to intentionally throw the fight, but Fighter A was sure he would lose, because he was injured, he was hurt, and he honestly thought Fighter B was a better fighter. Fighter A claims he would still fight his heart out but he thinks Fighter B will beat him, and places a huge bet on Fighter B. Sure, there is a obvious conflict of interest, but I haven't found anything that would make that conflict of interest illegal or make Fighter A subject to criminal/regulatory body fines. At most, they might have breached the code of conduct by the UFC.