The purpose of this study was to determine the utility of prostate specific antigen (PSA) level and Gleason score in the prediction of disease stage in men with newly diagnosed prostate cancer. 102 consecutive men, newly diagnosed with prostate cancer and candidates for radical therapy, underwent contrast enhanced pelvic CT and skeletal scintigraphy. Staging examinations used the TNM classification and were reported prospectively with the radiologist blinded to the patient's Gleason score and level of PSA. Lymph node metastasis was confirmed by CT guided biopsy, lymphadenectomy or response to therapy in some cases of massive disease. There were significant differences between the mean PSA values of 18 men with and 84 men without skeletal metastases (p = 0.01) and between men with locally confined and non-confined disease (p = 0.02). There was no difference between PSA values of 13 men with and 89 men without lymph node metastasis (p = 0.9). Only one man with CT evidence of nodal metastasis (N + ve) had a PSA value below 20 ng ml-1. Two men with Gleason scores below 6 were N + ve and both had PSA values over 20 ng ml-1. One man with skeletal metastasis had a PSA value below 20 ng ml-1 but had bone pain. For this study group if only those men with PSA values over 20 ng ml-1 had been examined, sensitivity for lymphatic and skeletal metastasis would have been 92%. Using this threshold about one-third would have been spared imaging investigation. In conclusion, pelvic CT and skeletal scintigraphy are unlikely to show metastatic disease in a man newly diagnosed with prostate cancer who has no suggestive clinical features, a PSA level below 20 ng ml-1 and a Gleason score below 6.