Priapism is a complication rarely seen in leukemia. We report a 19-year-old man presented with persistent painful erection of penis for over 24 hours at home. The patient had underwent immediate irrigation and decompression of priapism by urologist at emergency services of the hospital. This approach resulted in a flaccid penis later. During hospitalization, peripheral blood smear and bone marrow aspiration confirmed the diagnosis of chronic myeloid leukemia.