Priapism is a relatively uncommon condition that may present as a medical emergency associated with significant pain and anxiety in the veno-occlusive or low-flow variant. Pharmacologic advances and, specifically, the availability of intracavemosal alpha-agonist therapy have dramatically improved the prospects of resolution for patients with low-flow priapism presenting within the first few hours of the acute episode. High-flow priapism is not considered an emergency and treatment measures are typically conservative aimed at preservation of potency. Urologists, radiologists, and other health care personnel caring for the patient with priapism must be familiar with various etiologic factors implicated in low-flow and high-flow priapism to formulate a logical step-care approach. Differentiation of the low-flow from the high-flow state is perhaps the most critical initial diagnostic challenge that determines the sequence of further interventions including surgical shunts in low-flow priapism refractory to medical therapy.