The probability of survival of patients with gastric cancer depends upon depth of wall penetration by the primary tumour and metastatic lymph node burden. Radical lymphadenectomy may lead to prolonged survival but with increased morbidity. A computer program from Maruyama, National Cancer Centre, Tokyo enables evaluation of individual survival time and infiltration of lymph nodes. This analysis was applied to a German population. Computer-aided predictions were determined retrospectively using the prognostic factors of sex, age, Borrmann classification, histology, depth of wall penetration, location and diameter of the tumour. Data were collected from 222 patients at the Technical University of Munich (median age 66 years, sex ratio (M:F) 2:1), who had been operated on (72 per cent total gastrectomy, 28 per cent subtotal gastrectomy) for gastric cancer. The predicted results were compared with the postoperative pathological findings. The prediction of node metastases was highly accurate (lymph nodes 13-16, 96 per cent; 7-12, 89 per cent; 1-6, 82 per cent). These computer predictions may provide perioperative information of therapeutic value.