Transperineal 125-iodine seed implantation guided by transrectal ultrasonography and subsequent external beam irradiation was employed in the treatment of 32 patients with localized prostatic carcinoma (16 poorly differentiated). Follow-up is currently 35-98 months with a median of 65 months. Distant metastases have developed in 18 patients, of whom 11 have died from prostatic cancer. Median change in prostatic volume was a reduction of 35%. Re-biopsy or transurethral resection of the prostate was performed in 25 patients after 1-4 years, revealing still malignant histology in 10 (40%), of whom 8 have developed distant metastases or died from prostatic cancer. Fourteen patients suffered from late complications of which surgical intervention was indicated in five cases. Nine patients are presently free of progression and prostate specific antigen is less than 0.5 ng/ml in 8 of these. The future role of ultrasonically guided implantation in the management of prostatic cancer is discussed.