To compare extensive with limited lymph node dissection in the surgical treatment of gastric cancer, 320 patients undergoing gastric resection during 1981-1990 were divided into two groups. Although patients undergoing extended lymphadenectomy (n = 157) had a longer operating time (P = 0.0001) and a greater intraoperative blood transfusion requirement (P = 0.009) than those receiving limited dissection (n = 163), the incidence of postoperative complications (22.3 versus 28.2 per cent, P = 0.13) and the hospital mortality rate (3.8 versus 7.4 per cent, P = 0.12) were similar in the two groups. The 5-year survival rate after curative resection (117 and 121 patients after extensive and limited lymph node dissection respectively) was 65.4 versus 50.1 per cent (P = 0.01): 85.9 versus 82.2 per cent for stage I disease (P = 0.60), 66.1 versus 57.8 per cent for stage II (P = 0.82) and 48.7 versus 29.8 per cent for stage III (P = 0.02). Multivariate analysis using the Cox model showed that the extent of lymphadenectomy was an independent prognostic factor for survival (P = 0.01). The results support the value of extensive lymph node dissection in the surgical treatment of gastric carcinoma.