PURPOSE: The results of a 1997 meta-analysis of the rates of erectile function after external beam radiotherapy (EBRT) and radical prostatectomy have been widely used in patient and professional education materials and as a reference against which new findings are compared. With a number of recent publications, it is now possible to update this analysis and compare brachytherapy with or without EBRT with EBRT alone, standard and nerve-sparing radical prostatectomy, and cryotherapy. METHODS: A comprehensive literature review and subsequent meta-analysis of the rates of erectile dysfunction associated with the treatments of localized prostate carcinoma was conducted. A simple logistic regression analysis was used to combine the data from the 54 articles that met the selection criteria. RESULTS: The predicted probability of maintaining erectile function after brachytherapy was 0.76, after brachytherapy plus EBRT 0.60, after EBRT 0.55, after nerve-sparing radical prostatectomy 0.34, after standard radical prostatectomy 0.25, and after cryotherapy 0.13. When only studies reporting > or = 2 years follow-up were considered, the only significant change was a decline in the probability for nerve-sparing radical prostatectomy. No brachytherapy studies had a follow-up of > or = 2 years. When the probabilities were adjusted for age, the spread between the RT methods and surgical approaches was greater. CONCLUSION: The differences in the probability of maintaining erectile function after different treatments of localized prostate cancer are significant.