Decision making for treatment of localized prostate cancer is often guided by therapeutic side-effect profiles. We sought to assess health-related quality-of-life outcomes for patients 48 months after treatment for localized prostate cancer. Men treated for localized prostate cancer (N=475) were evaluated before treatment and at 11 intervals during the 48 months after intervention. Changes in mean health-related quality-of-life scores and the probability of regaining baseline levels of health-related quality of life were compared between treatment groups. All statistical tests were two-sided. Urinary incontinence was more common after prostatectomy (n=307) than after brachytherapy (n=90) or external beam radiation therapy (n=78) (both P < .001), whereas voiding and storage urinary symptoms were more prevalent after brachytherapy than after prostatectomy (both P < .001). Sexual dysfunction profoundly affected all three treatment groups, with a lower likelihood of regaining baseline function after prostatectomy than after external beam radiation therapy or brachytherapy (P < .001). Bowel dysfunction was more common after either form of radiation therapy than after prostatectomy. These results may guide decision making for treatment selection and clinical management of patients with health-related quality-of-life impairments after treatment for localized prostate cancer.