A 13-year-old girl was transferred from a private clinic to our emergency department due to lower abdominal pain and acute urinary retention. Radiologic evaluation showed an imperforate hymen with hematocolpometra. In the emergency department, an imperforate hymen is a rare cause of acute urinary retention. Usually, the diagnosis of a congenital inperforate hymen can be made by inspection of the perineum; however, in many cases, an extensive radiologic evaluation must be performed because of misdiagnosis. The emergency physician should consider an imperforate hymen in girls with lower abdominal pain and urinary retention.