Forty consecutive patients were admitted alive to the operating theater with ruptured infrarenal aoritc aneurysms in a 3-year period and were assessed preoperatively with two scoring systems: the POSSUM (physiological and operative severity score for the enumeration of mortality) and the APACHE II (acute physiologic and chronic health evaluation). The aim of the study was to investigate the capacity of the two scores to predict the patients' outcome. The operative mortality of the series was 55% (22/40). The average POSSUM score was 63.3 for survivors and 66.5 for the nonsurvivors (difference not statistically significant). APACHE II score averaged 11.3 in survivors and 14.5 in nonsurvivors (p = 0.02). APACHE II score 17 was the threshold value with the highest combined specificity and sensitivity; however, at this point the positive predictive value for a death was 92% and the negative predictive value was 63%. Interestingly, the only single factor in univariate analysis affecting mortality was the preoperative platelet count and is not taken into account in neither of the two scoring systems. POSSUM failed in predicting the outcome of ruptured infrarenal aortic aneurysms. APACHE II was a good predictor of outcome; however, its power to predict the outcome in any given individual patient was limited. As precise prediction is impossible, repair in every patient should not be denied.