The influence of operative treatment and chemotherapy on the prognosis in 93 gastric cancer patients with liver metastasis was studied. Chemotherapy included the systemic administration of mitomycin C (MMC) (39 patients), an intra-hepatoarterial infusion of MMC (MMC IAC group) (19 patients) and an intra-hepatoarterial infusion of MMC and cisplatin (CDDP) (MMC + CDDP IAC group) (24 patients). Either MMC or MMC and CDDP were given in 1-4 courses every 3-4 weeks from the first one to two post operative weeks. The response rate was 4 per cent (1/23), 29 per cent (5/17) and 73 per cent (17/23) for MMC systemic administration, MMC IAC and MMC + CDDP IAC, respectively, with a significantly high rate of effectiveness for the MMC + CDDP IAC. In addition, regarding the median survival period, the MMC + CDDP IAC group showed 11.8 months, as compared with 2.9 months for other chemotherapeutic treatments, indicating a good prognosis regardless of any possible resection of the primary lesion. A Cox proportional hazard model revealed the treatment by MMC + CDDP IAC alone to be a significant independent factor. These results indicated that MMC + CDDP intra-arterial chemotherapy is an effective approach to gastric cancer with liver metastasis.