PURPOSE: The acute scrotum is a clinical syndrome that is defined as an acute, painful swelling of the scrotum or its contents. The symptoms and signs of acute scrotum are similar and its pathognomonic features are rarely detected. This study was performed to find a proper way to diagnose and treat acute scrotum promptly and correctly. METHODS: From January 1990 through December 1999, 31 cases of pediatric patients hospitalized in this center with acute scrotum were analyzed for diagnosis, seasonal incidence, age distribution, time interval from the onset of symptoms to admission, symptoms and signs, laboratory and radiologic findings and therapeutic details. RESULTS: Acute scrotum included 13 cases of testicular torsion(41.9%), 9 cases of acute epididymitis(29.0%), five cases of torsion of appendages (16.1%), and four cases of orchitis(12.9%). Twelve cases(38.7%) were observed from March to May. The average time interval from the onset of symptoms to admission was 11.6 hours and 46.1 hours for testicular torsion and acute epididymitis, respectively. All testicular torsion showed no cremasteric reflexes. Only three out of 13 cases of testicular torsion were successfully treated with manual detorsion. Seven cases underwent testis reduction and orchiopexy. The remaining three cases of testicular torsion showing the necrosis of testes were treated with orchiectomy. CONCLUSION: Color doppler ultrasonography, testicular scintigraphy, and physical examination such as cremasteric reflex are useful for diagnosis. Surgical procedures can be the most effective treatment for testicular torsion, and the antibiotic treatments for both epididymitis and orchitis. However, conservative treatment can be effective in the case of torsion of appendages.