The diagnosis of obturator hernia is difficult, and delayed treatment is associated with serious complications. Recently, computed tomography (CT) has been used successfully for establishing a correct diagnosis. We encountered nine cases of obturator hernia from 1988 to 1997. All the patients were elderly women. In six of them, a correct diagnosis was established by emergent CT scan. In two of the remaining cases, diagnosis could not be established because of unavailability of CT, and the other patient was diagnosed correctly based on clinical features, including a positive Howship-Romberg sign. Surgical repair was performed successfully. One patient died postoperatively because of septicemia associated with anastomotic leakage. Our cases indicate that emergent CT scan is useful for the diagnosis of obturator hernia, particularly in elderly patients presenting with ileus of unknown origin.