Henoch-Schönlein purpura (HSP) belongs to the category of systemic small-vessel vasculitis. Although long-term outcome is generally good, serious complications may occur. Thrombosis and priapism have been reported only as extremely rare complications of HSP. We describe a 37-year-old man who developed recurrent thrombotic events shortly after he had been diagnosed as having HSP. Although he had additional risk factors for thrombosis, such as prothrombin G20210A mutation and use of celecoxib before the last episode, temporal relation of the thrombotic attacks to the onset of HSP suggest that the disease itself may lead to a prothrombotic state. This case is the first adult HSP patient with priapism, which probably developed secondary to thrombosis of the dorsal penile vein.