PURPOSE: To evaluate the usefulness of transperineal sonography of the prostate in patients with previousabdominoperineal resection. MATERIALS AND METHODS: Transperineal prostatic sonograms were obtained from ninepatients with abdominoperineal resection. The shortest distance between the probe and the prostate gland, itsvolume, and its internal and external structures were evaluated for image quality, shape, border, and the degreeof distortion in internal echo. Because the number of patients was small, statistical analysis was not performed. RESULTS: Transperineal sonography of the prostate in eight patient was obtained at ease, except that one of ninepatients was not able to continue the procedure because of severe tenderness of the perineum and poor cooperation.Acceptable images of the prostate gland and their adjacent structures were obtained in one patient with less than1cm between the probe and prastate gland, three of four with between 1cm and 1.5cm, and one of three with morethan 1.5cm. CONCLUSION: In patients with previous abdominoperineal resection, transperineal sonography of theprostate may be a good imaging modality.