Effectiveness of prophylactic extensive lymph node dissection (PELD) plus postoperative long term combination chemotherapy (PLCC) for patients with curatively resected gastric carcinoma was assessed in terms of the degree of serosal invasion and lymph node metastasis. Either the Group 1 and Group 2 lymph nodes were eradicated by PELD. PLCC included intermittent intravenous administration of mitomycin C (0.4 mg/kg intraoperatively followed by 0.2 mg/kg every 3 months) and oral administration of Tegafur (600-800 mg/day) and PSK (3.0 g/day), an immunostimulator, for as long a period as possible. PELD alone resulted in a cure when the malignancy was confined to the mucosal and muscular layers of the stomach as well as to the Group 1 lymph nodes. In cases when the carcinoma involved the serosa and/or the Group 2 lymph nodes, the 5 year survival rate was about 55 per cent the PELD and PLCC groups, such being significantly higher than about 27 per cent in the PELD alone group. Therefore, PELD plus PLCC is highly effective for advanced gastric carcinoma, under a condition of curative resection.