Thirty patients (6.9%) had a Boey score of 2 or more. The mortality rate increased progressively, with increasing numbers of Boey risk factors: 1.5%, 14.4%, 32.1%, and 100% for 0, 1, 2, and 3 factors, respectively (P<.001, Pearson χ2 test). The morbidity rates for 0, 1, and 2 Boey risk factors were 17.4%, 30.1%, and 42.1%, respectively (P = .002, Pearson χ2 test). The median APACHE II score was 5 (range, 0-24). The APACHE II score was higher among the nonsurvivors than among the survivors (P<.001, Mann-Whitney U test) and among patients with postoperative complications (P<.001, Mann-Whitney U test). The median size of the ulcer was 5 mm. When compared with that of the survivors, the median ulcer size of the nonsurvivors was significantly larger (P<.001, Mann-Whitney U test). Similarly, the ulcer was significantly larger in patients with morbidity (P<.001, Mann-Whitney U test). It appeared that the Boey score, the APACHE II score, and the ulcer size independently predicted mortality and morbidity of patients with perforated peptic ulcer. Using multivariate analysis (logistic regression, forward stepwise), patients' likelihood of death could be predicted by the Boey score (P = .02) and the APACHE II score (P<.001) but not the ulcer size (P = .88). In terms of morbidity, only the APACHE II score (P<.001) could predict the risk of complications (logistic regression, forward stepwise); the Boey score and the ulcer size were nonsignificant (P = .88 and P = .47, respectively).