PURPOSE: The incidence of complications after gastric tumor surgery has been decreasing, because of properly chosen and improved surgical techniques and procedures. But the incidence of several complications that result in relatively high mortality remains stubbornly high. To predict and prevent postoperative complications in gastric tumor treatment, we retrospectively analyzed gastric tumor patients who underwent elective gastrectomy. METHODS: This is a retrospectively study of 1,028 patients with gastric tumor who underwent elective surgery at the Department of Surgery, Ulsan University College of Medicine and Asan Medical Center between January 1999 and December 1999. Non-curative surgery was defined in cases of peritoneal seeding, distant lymph node metastasis and residual tumor in the resection margin. RESULTS: There were no significant differences in age, hemoglobin, albumin, operation time, extent of lymph node dissection, surgical procedure or stage (P>0.05). The complication rate after non-curative resection was higher (11.7%) than that for curative resection (5.9%) (P<0.05). The complication rate was higher (12.3%) in patients who had combined diseases than in those who did not (4.9%) (P<0.05), and was higher (13.2%) in patients who underwent combined resection than in those who did not (5.0%) (P<0.05). CONCLUSION: In patients who had combined diseases and underwent combined resection, the complication rate was significantly higher. But, if more attentive preoperative evaluation and intraoperative caution are exercised in patients who exhibit preoperative risk factors, the incidence of post operative complication is expected to diminish.