Priapism is a very rare problem in childhood. Although sickle cell disease and leukemia may produce persistent erection, juvenile priapism is most commonly idiopathic. The physiology and pathology of erection are reviewed, and the pathomechanisms of diseases which may produce priapism are described. If red cell sickling and leukemia are excluded, immediate surgical intervention by either corporosaphenous or corporospongiosum shunts is recommended for resolution of priapism and preservation of potency. A case of juvenile priapism is presented in which HCG medication as underlying factor is discussed.