The hospital records of 50 patients treated for ruptured abdominal aortic aneurysms during the past ten years were reviewed. Nine patients in cardio-pulmonary arrest on arrival at our emergency room and 3 resuscitated patients were included in this study. The patients were classified into four groups: the non-shock group (17 cases), shock group (21 cases), post-cardiac resuscitation group (3 cases) and the cardio-pulmonary arrest on arrival (CAPOA) group (9 cases). The mortality rates including preoperative death in each group were 5.9% (non-shock), 57.1% (shock), 66.7% (post resuscitation) and 88.9% (CPAOA). The overall mortality rate was 46%, although the mortality rate in patients receiving graft replacement was 35.6%. The mortality in the non-shock group was significantly lower than in the other three groups. Longer duration of shock, lower preoperative systolic blood pressure level, longer operative time, greater blood loss and greater amount of blood transfused were risk factors in cases of graft replacement. The risk factors associated with preoperative death were advanced age and acidosis due to severe shock. The correct initial diagnoses were made in prior hospital in 28 cases. Incorrect diagnoses, which were made more often in non-shock patients than in patients in shock, were abdominal pain of unknown origin in 6, ureterolithiasis in 4, lumbago, appendicitis and gastritis in 2 cases each. The delayed diagnosis might have resulted in more severe shock or cardiac arrest. In conclusion, to reduce the mortality of ruptured AAA, correct initial diagnosis and expeditious preoperative management are most important.