We have studied the incidence and prognosis of N4 node (para-aortic lymph node) metastases in gastric cancer in 434 patients who had been referred to our department for surgical treatment during the period between 1978 and 1988. N4 nodal involvement was found in 76 (17.5%) of 434 patients who had received a laparotomy with resection, and in 42 (10.5%) of 400 patients who had "curative" resection. When the surgeon assessed that the patients had metastasis in para-aortic lymph nodes, the para-aortic lymph nodes lying above and below the left renal vein were completely removed (R4 gastrectomy). During this period, 42 patients with N4 nodal involvement underwent "curative" resection by R4 gastrectomy. Their treatment results were compared with those of 32 patients who underwent subtotal or total gastrectomy (R2 or R3 gastrectomy) without resection of metastases of para-aortic lymph nodes ("palliative" resection). The operating time and the operative mortality rate were similar in both groups (R4 vs R2 or R3 gastrectomy). The patients who had undergone "curative" resection (R4 gastrectomy) had a significantly higher five-year survival rate than those who had received "palliative" resection. The R4 gastrectomy is a rational and useful surgical procedure for treating patients with N4 nodal involvement.