Hydrocoele of the canal of Nuck is a rare condition in adult women caused by a failure of complete obliteration of the canal of Nuck. It may be likened to a patent processus vaginalis in men. In most cases, the diagnosis is made during surgery as it is often mistaken for an inguinal hernia. We report a case where the diagnosis of this condition was made preoperatively on imaging. The salient anatomy, clinical features, radiological images and surgical management are discussed and the medical literature reviewed.