Epididymo-orchitis, an uncommon cause of acute scrotum in prepubertal boys, is infection or inflammation of epididymis and testis. Epididymo-orchitis may be associated with urinary tract infections or reflux of urine predisposed by an underlying vasal anomaly. Two infants with anorectal malformations who presented with acute scrotum are reported. The surgical exploration of the testes showed findings consistent with epididymo-orchitis. Further radiological investigations of urinary tract showed vasal anomalies in both patients. If a patient with anorectal malformation presents with acute scrotum, epididymo-orchitis should be suspected initially. Evaluations should be directed toward defining predisposing vasal anomaly, and appropriate therapeutic measures should be undertaken to prevent recurrences. J Pediatr Surg 33:1834-1836. Copyright (C) 1998 by W.B. Saunders Company.