Assessment of sexual function following potentially curative local treatment for carcinoma of the prostate gland has resulted in wide ranges of potency preservation rates, which may be because of differences in the evaluated patient populations, mode of data collection, and length of patient followup. Quality-of-life data are most reliable when obtained by patient-administered and validated quality-of-life instruments. In the Schiffler Cancer Center's prostate brachytherapy unit, healthcare professionals utilize the specific erectile questions of the International Index of Erectile Function to ascertain pre- and post-treatment erectile function. Documentation of sexual function following all local treatments, including prostate brachytherapy, may help to clarify the etiology of treatment-induced erectile dysfunction (ED), improve treatment for ED, and, ultimately, improve qualityof-life outcomes. Fortunately, the majority of patients with brachytherapy-induced ED respond favorably to sildenafil citrate.