Objective: To evaluate the effect of sildenafil in Brazilian patientswith erectile dysfunction secondary to spinal cord injury. Methods:Participants were examined at the time of enrollment and two andsix weeks later. Baseline and follow-up data on sexual functionwere collected. After the second week, the initial dose of sildenafil(50 mg) could be adjusted according to efficacy and tolerability.Efficacy was assessed primarily through the scores on questions 3and 4 of the International Index of Erectile Dysfunction. Secondaryanalyses included questions and domains of the index, globalefficacy evaluation, percentage of success in sexual intercourseattempts, answers to the Quality of Life and Erectile FunctionQuestionnaire, and partner’s satisfaction. Results: Ninety-onepatients were evaluated as to efficacy and 94 as to safety. Medianage of patients was 33 years, and median time between spinal cordinjury and study enrollment was three years. Sildenafil produceda significant increase in the mean scores of questions 3 and 4(p < 0.001 in both comparisons), as well as in other questionsand in all domains of the International Index of Erectile Dysfunction.Improved erections were reported by 89% of patients, and theproportion of successful sexual intercourse attempts went from6 to 74% (p < 0.001). Mean scores on the Quality of Life andErectile Dysfunction Questionnaire increased from 60 to 74%(p < 0.001). Ninety percent of 42 women reported being moderatelysatisfied to very satisfied with their partners’ treatment. The mostcommon adverse events were headache (16%), flushing (11%) andnasal congestion (10%). Conclusions: Sildenafil proved to be safeand effective in treating Brazilian men with erectile dysfunctionsecondary to traumatic spinal injury.