Pre-operative serum prostate specific antigen (Tandem-R assay), T category, Gleason score and the metastatic (M 1) status of a consecutive series of 60 patients with newly diagnosed carcinoma of the prostate were studied prospectively. The results revealed that, of these variables, pre-operative serum PSA (> 100 ng/ml) was the single most important indicator of metastatic disease, with 100% predictive value. With this alone, 83.3% of M1 disease could be correctly identified. For the remaining 17%, however, we advocate a high index of suspicion if the tumour is T3-T4 category on digital rectal examination (predictive value = 71.4%) and has a high grade with a Gleason score 8–10 (predictive value = 81%).