The results for 162 patients who underwent curative gastrectomy for gastric cancer from January 1988 to June 1994 were analysed statistically with special reference to the effect of lymph node dissection. Median survival was 69.3 months and the overall cumulative 5-year survival rate was 50.2 (95 per cent confidence interval (c.i.) 41.6-58.1) per cent. By univariate analysis age, histology, depth of tumour invasion, node involvement, number of metastatic lymph nodes and type of lymphadenectomy were found to be significant factors related to survival time. Multivariate analysis with the Cox model and stratified for tumour node metastasis stage revealed that only the number of metastatic nodes (P = 0.04) and the extent of lymphadenectomy (P = 0.003) affected survival independently. With respect to D1 lymphadenectomy, the relative risk associated with D2 and D4 lymphadenectomy was respectively 0.61 (95 per cent c.i. 0.34-1.10) and 0.26 (95 per cent c.i. 0.12-0.60). The 5-year survival rate was 28 per cent for patients who had a D1 dissection, 63 per cent for those who had D2 and 68 per cent for those who had D4. These results suggest that extended lymphadenectomy (D2) and especially superextended lymphadenectomy (D4) can improve survival in patients with gastric cancer.