Lionfish (Pterois volitans) are venomous fish most often found as aquarium pets throughout the United States. Lionfish envenomations frequently occur on the upper extremities, with pain as the predominant symptom. Immersing the injured part in warm (45 degrees C) water is considered the first and foremost important treatment as it is reported to relieve pain and inactivate the venom. Other methods of analgesia are discussed. We present a case of lionfish envenomation that failed to respond to warm water immersion.