Erectile dysfunction (ED) is a common condition in aging men, but little is known about the prevalence of ED in some specific groups of patients such as those with end-stage renal disease (ESRD). A cross-sectional study was conducted to determine the prevalence of ED in ESRD patients undergoing hemodialysis in two clinics of Londrina, Brazil. The prevalence and severity of ED were assessed using the International Index of Erectile Function and a single global question. The dependence of ED on independent variables was evaluated by logistic regression. Some degree of ED was found in 86.4% of our sample (n=118). Complete ED was reported by 25.4% of subjects, moderate ED by 35.4%, and minimal ED by 24.6%. Subjects < 50 y old had a prevalence of moderate/complete ED of 52.6%, whereas in men > or = 50 y old, it was 70.5%. Age, diabetes, and low income were significantly associated with ED. Although highly prevalent, only a low percentage of uremic ESRD patients on hemodialysis were being treated for ED. Our data suggest that ED is related to uremia and other comorbid conditions that often accompany ESRD.