This article describes 51 cases of Scorpaenidae envenomation, 45 of which were lionfish stings to aquarists or fish handlers. The primary manifestation of envenomation in all victims was intense local pain. Various other local and systemic symptoms were also noted. Immersion in hot water produced either complete (80%) or moderate (14%) symptomatic relief in 94% of the victims. This simple and effective treatment was generally unknown to emergency personnel treating these patients.