This study was conducted to see whether the accuracy in predicting liver metastases in gastric cancer patients increased when DNA aneuploidy and c-erbB-2 gene products were analyzed besides other clinicopathologic features. Aneuploidy was observed in 32 out of 74 tumors (43%); these included 62% of those tumors in patients with liver metastases, 43% of those with peritoneal dissemination and 26% of those in the 5-year survival group. Aneuploidy was positively correlated with the prognosis and degree of blood vessel invasion but not with lymph node metastases or lymphatic permeation. Positive staining for the c-erbB-2 gene product was detected in 19 out of 89 tumors (21%). This staining was not related to any of the clinicopathologic features examined. Multivariate analysis revealed that the degree of blood vessel invasion was the factor that most strongly correlated with liver metastases. The prognostic value of aneuploidy was significant (p < 0.05) but much smaller than that of blood vessel invasion (p < 0.0001), interstitial tissue reaction (p = 0.02), Borrmann type classification (p = 0.03). Analyses of DNA aneuploidy and c-erbB-2 gene expression in the primary tumor of gastric carcinoma to improve the accuracy of predicting liver metastasis seem to be of limited clinical value at present.