Henoch-Schönlein purpura is a systemic vasculitis and sometimes presents as acute scrotal swelling in children. We report a case of Henoch-Schönlein purpura with acute scrotal swelling, which was correctly diagnosed based upon local physical findings. Scrotal ultrasonography showed normal testes and hydrocele testis around the affected testis 3 hours after the sudden onset of the pain. The scrotal symptoms improved in 2 days with steroid therapy. Scrotal ultrasonography was useful to diagnose Henoch-Schönlein purpura with scrotal involvement. Steroid treatment appeared to be effective for this condition.