Eight cases of snakebite occurred in seven of 11 captive Rocky Mountain elk (Cervus elaphus nelsoni) during June and July 1987. Severity of reactions to envenomation varied; affected elk presented with combinations of signs that included painful swelling restricted to the face and muzzle, submandibular edema, inspiratory dyspnea, epistaxis, frothy, blood-tinged nasal discharge, epiphora, anorexia and anxiousness or depression. We observed puncture wounds in only two cases. Treatment consisted of dexamethasone (about 0.1 mg/kg subcutaneously, single dose) and procaine penicillin G (about 25,000 IU/kg subcutaneously, once or twice daily, for 5 to 6 days), as well as revaccination using clostridium and tetanus toxoids. Swelling resolved and elk recovered in 3 to 5 days without complications. Using immunodiffusion, we detected serum antibodies to prairie rattlesnake (Crotalus viridis viridis) venom in six of seven affected elk, demonstrating seroconversion in three cases and anamnesis in one elk bitten twice. Venom was undetectable in any serum samples using similar techniques.