Obturator hernia is relatively rare and occurs mostly in elderly, thin, multiparous women. Recent reports have highlighted the importance of pelvic computed tomography (CT) for the preoperative diagnosis. Thirty-six patients with an obturator hernia operated in our hospital were divided retrospectively into two groups (group A: 18 operations from 1973 to 1986, before we used CT; group B: 18 CT cases from 1987 to 1995). Preoperative diagnoses, operative procedures, and postoperative course were reviewed. No statistically significant differences were found between groups A and B in terms of patient characteristics. Rates of accurate preoperative diagnoses were significantly higher in group B: 39% (7/18) in group A and 78% (14/18) in group B (p = 0.018). The intraoperative findings, occurrence of postoperative complications, and overall mortality rates were similar between the two groups. There were four postoperative deaths (mortality rate 11%). Three of four patients who died had panperitonitis because of small bowel perforation. The correct preoperative diagnosis of obturator hernia was facilitated by CT of the pelvis, but it has no impact on patient outcome. Early diagnosis and surgical intervention are essential for this rare entity.