Obturator hernias are relatively rare. In the past 15 years at the Mayo Clinic, eight patients underwent nine operations for repair of 11 obturator hernias, which represented 0.073 per cent (11 of 15,098) of all hernias repaired at this institution. Elderly women with chronic disease were most frequently affected. Symptoms were usually intermittent; mechanical small intestinal obstruction was the most common presenting condition, followed by pain in the thigh or groin area. The Howship-Romberg sign was found in only two patients, and a correct preoperative diagnosis was made in only one patient. Midline abdominal incisions were made in all patients. Incarcerated ileum was the most frequently encountered organ in the hernia sac. Surprisingly, foci of endometriosis in the obturator defect accounted for symptoms in two patients with three obturator hernias. Right-sided obturator hernias outnumbered left, and bilateral obturator hernias were found synchronously in two instances and metachronously in one instance. The often debilitated state of the patients with obturator hernia and the frequent delay of diagnosis combined to produce significant operative morbidity and mortality rates.