Black widow spider envenomation (BWSE) is commonly associated with severe abdominal pain, muscle cramping, and hypertension. Treatment is primarily symptomatic with the use of opiates and benzodiazepines. Priapism is a complication of BWSE that has only rarely been reported. We describe a 17-month-old male who developed priapism after known BWSE. His priapism did not respond to opiates or benzodiazepines, and he was treated with black widow spider antivenin. Complete detumescence followed within several hours. The patient required no additional opiates for pain and was discharged from the hospital the following day. The patient's rapid improvement after antivenin suggests its efficacy in treating BWSE-associated priapism.