Twelve variables were studied for possible prognostic value in 242 patients with adenocarcinoma of the stomach. Eight of these had a statistically significant effect on survival in univariate analyses. A multivariate analysis of 196 patients showed that the most significant differences in survival could be explained by 3 independent variables acting simultaneously, namely stage of disease, Sialyl Tn antigen (STn) expression and aneuploidy of the tumour cells. By adding scores for stage (1-4 points), STn expression (0-1 points) and ploidy (0-1 points) a risk score based on these 3 variables defined the patients into 6 different risk groups with statistically highly significant differences in survival (chi 2 = 107.74, DF = 1, p < 0.0001). Application of the risk score improves the prediction of outcome, may help in choosing patients for different treatment modalities, and allows more accurate stratification in clinical trials.