OBJECTIVE We investigated the frequency of para-aortic lymph node involvement and evaluated the effects on survival of dissection of these lymph nodes in patients with N4 node metastasis. METHODS One hundred and forty nine gastric cancer patients with N4 node dissection were analyzed. Total gastrectomy with splenectomy or pancreatosplenectomy was performed in 99, distal gastrectomy 48, pancreaticoduodenectomy 3, and proximal gastrectomy with splenectomy 2. RESULTS N4 nodal involvement was found in about 30-40% of operable patients with Borrmann's type 3 or 4 tumor, with tumor >8 cm in size, with tumor throughout the entire or in the upper third of the stomach, with tumor invasion to the serosa or adjacent structures, with N2 or N3 regional lymph node metastasis, and with undifferentiated histological type. The survival was quite poor. However, in patients without N3 nodal involvement or intraperitoneal free cancer cells, the survival after resection of tumor with N4 nodal involvement was relatively favorable. CONCLUSIONS The resection of these involved lymph nodes can be expected to be beneficial in patients without extensive serosal invasion and without extensive lymph nodal involvement such as N3 nodes. Patients with tumor in the upper third of the stomach are appropriate candidates for N4 node dissection.