An imperforate hymen usually presents within a few days of life with a lower abdominal mass, sometimes associated with urinary retention. Intrauterine stimulation of the infantâ€™s cervical mucous glands by ma-ternal oestrogens causes accumulation of secretions (mucocolpos). The imperforate hymen can be seen bulging through the introitus and treat-ment consists of incising the hymen. Occasionally, an imperforate hymen is not detected in the newborn period and presents at puberty with p amenorrhoea or a painful lower abdominal mass from a haematocolpos. Treatment again comprises incision of the hymen and should be per-formed under general anaesthesia.