Idiopathic neonatal priapism is a rare pathology with an estimated incidence of 15/10,000 births. Despite the distressing clinical picture, it is a relatively benign pathology. We report a case of idiopathic neonatal priapism treated in our department, in a newborn on day 1 of life with no known pathological family history. The clinical picture was characterized by a permanent, painless erection of the penis with no associated signs or change in skin color. No etiology was revealed by the clinical and paraclinical assessment. Treatment consisted of simple monitoring. Complete detumescence is obtained after fourteen days of evolution. The prognosis was favorable with conservation of the physiological erection at six months of follow-up.