Introduction: A single institutional surgical trial for gastric cancer had demonstrated increased morbidity but not mortality. This report analyzes risk factors affecting morbidity. Methods: Risk factors for morbidity in 221 patients treated with curative intent were evaluated in a prospective randomized trial comparing D1 and D3 surgery for curable gastric cancer. Results: The surgeon's experience after 25 nodal dissections had no influence on surgical or overall complications, nor did the patients' co-morbidity (e.g., respiratory system disease, cardiac disease, diabetes mellitus). Distal pancreatectomy negatively affected surgical morbidity [relative risk (RR) 6.21, 95% confidence interval (CI) 1.869-20.626] and overall morbidity (RR 5.50, 95% CI 1.671-18.082). All of the patients with a distal pancreatectomy underwent concomitant splenectomy. Multivariate analysis found splenectomy and nodal dissection to be the only two independent risk factors adversely affecting operative morbidity. The RR of splenectomy for surgical complications was 4.19 (95% CI 1.327-13.208), and for overall complications it was 3.88 (95% CI 1.259-11.973). The RR of nodal dissection for surgical complications was 2.51 (95% CI 1.336-4.730), and for overall complications it was 1.93 (95% CI 1.149-3.255). Conclusions: Splenectomy (with or without pancreatectomy) and nodal dissection are risk factors for operative morbidity but not mortality.