In the last eight years, 60 patients with carcinoma of the prostate in an advanced stage underwent transrectal ultrasound examinations of the prostate both before and after treatment with LHRH analogues, alone or associated with antiandrogens. Mean follow-up was 30 months (9-96 months) and mean survival 33 months (9-81). In all patients, the volume and echogeneicity of the prostate were assessed before treatment and once every three months thereafter. A significant reduction in volume was observed in 91% of the cases (54/60), while a variation in the echogeneicity was noted in 80% of the patients (48/60); these data do not seem to have been affected by the type of treatment administered. The greatest reduction in volume occurred during the first three months, after which a virtually constant volume was observed. Metastatic progression occurred in 29 of the 60 patients assessed, whereas no increase in prostate volume was demonstrated by ultrasound in 18 of these patients. These data, reported by other authors, too, may indicate that transrectal ultrasound examinations alone cannot constitute a complete follow-up in prostatic carcinoma: they can only show local progression and should therefore be associated with other diagnostic methods, in particular the specific prostate antigen.