BACKGROUND: The APACHE scoring system of the Health Care Financing Administration (HCFA) has been being used for serious patients. The scoring system is composed of acute physiologic variables and chronic disease. METHODS: Among patients who underwent emergency operations from 1992 to 1997 because of gastrointestinal perforation, we analyzed 110 cases with five kinds of diseases: duodenal ulcer perforation, small bowel perforation, perforated appendicitis, gastric ulcer perforation and colon perforation. RESULTS: The results were as follows: 1) The preoperative APACHE II scores ranged from 0 to 21. The scores of 64 cases (60.9%) were from 0 to 5. 2) There were no death in case for which pre-peration APACHE II score was from 0 to 10, 25% of the mortality occurred in cases with scores from 11 to 15, 50% in those with scores from 16 to 20, and 100% in those with scores above 21. 3) The APACHE II score decreased continuously from the 3rd to the 7th postoperative day. 4) The preoperative APACHE II scores in gastric ulcer perforation patients were significantly higher than those in duodenal ulcer perforation patients. In the cases of gastric and duodenal ulcer perforations, the APACHE II scores in patients who underwent primary closure were higher than the scores in those who underwent a more definitive operation. 5) In death cases, all of their APACHE II scores were higher at the 3rd postoperative than at the 7th postoperative day, but their APACHE III scores continuously increased postoperatively. CONCLUSIONS: It is thought that the APACHE scoring system is more reliable than clinical experience in the classification of patients by operative risk and in estinating the result and giving a prognosis. Thus, the principle of treatment should be established by estinating patient's score before the operation. Careful preoperative management is necessary for patients with scores more than 10. Because patientswith scores more than 21 have very a high mortality, operative time and method must be carefully decided. The APACHE III scoring system seems to be more sensitive than the APACHE II scoring system in predicting deaths and further investigations and clinical applications should be performed.