BACKGROUND: Due to the variety of differential diagnoses causing acute scrotum and their possible consequences, this finding is a challenge for diagnostic and therapeutic management in the daily clinical practice of paediatric medicine. PATIENTS AND METHODS: Through a defined time period, all consecutive paediatric patients of a tertiary surgical centre aged up to 16 years who were diagnosed with and treated for primary acute scrotum were prospectively registered and retrospectively evaluated for patient, finding and treatment (intervention) associated specifics in this systematic unicentric observational study (design: case series) to reflect daily clinical practice. RESULTS: A total of 141 cases with acute scrotum were enrolled in the study during the 10-year period from January 2000 to December 2009. Eight percent of cases (n = 11) showed bilateral findings. There were two age peaks: newborns and puberty. The most common diagnoses were epididymitis and orchitis (26 %), torsion of the testicular appendix (22 %) and testicular torsion (21 %). Trauma, hydrocele, inguinal hernia, idiopathic scrotal oedema and tumours were rather rare differential diagnoses as possible causes for an acute scrotum. The mean period of discomfort, complaints and symptoms up to presenting in the outpatient clinic was 24 hours. For sixty percent (n = 84, i.e., all patients treated conservatively and 43 % of the operated patients) an imaging study was obtained with ultrasound or Doppler ultrasonography, respectively. Two thirds of the patients underwent an operative exploration. The orchiectomy rate in testicular torsion amounted to 40 %. In one newborn, a bilateral orchiectomy was necessary. In patients with unilateral orchiectomy, a prophylactic fixation of the contralateral testis was performed preferentially at 4-8 weeks after the initial intervention even though a simultaneous procedure is being increasingly used. CONCLUSIONS: In approximately one fifth of registered patients, a testicular torsion is present causing the acute scrotum, and leading to an obligatory surgical intervention. Various causative differential diagnoses can be clarified by precise medical history and exact physical examination. Imaging procedures can be helpful in decision-finding. Finally, the clinical finding is crucial and decisive. If a testicular torsion cannot reliably be excluded by clinical investigation or imaging, an immediate surgical exploration of the testis has to be performed.