Torsion of a spermatocele on its pedicle is an extremely rare clinical condition that mimics acute testicular torsion. This rare condition has not been well characterized. Here, we report a case of torsion of a spermatocele. The present case is the 5th case of torsion of a spermatocele and the first report in a patient with a history of scrotal trauma. A tender cystic mass adjacent to the normally appearing testicle in the scrotum is highly significant for the differentiation from other types of acute scrotum. Torsion of a spermatocele should be considered a differential diagnosis of acute scrotum in adolescents and adults.