The pathogenesis of Peyronie's disease still remains an enigma and few epidemiological studies are available. The purpose of this study was to determine the prevalence of Peyronie's disease in males older than 50 y. From 26 to 30 July 1998, 1071 men attended the 'Prostate Cancer Awareness Week of Santa Casa Hospital, Porto Alegre, Brazil'. In the prostate exam they also consented to be screened for Peyronie's disease. They underwent the 5-item International Index of Erectile Function (IIEF-5) questionnaire for evaluation of the erectile condition. The presence of a well-defined plaque in the penis was the diagnostic criterion for Peyronie's disease. The men were examined by five senior residents, under supervision by the staff Urologist. Men younger than 50 y as well as patients under intracavernous injection therapy for erectile dysfunction were excluded from the study. Chi2 test was used for statistical analysis. Nine hundred and fifty-four (89.1%) out of the 1071 men with a mean age of 62 y (ranging from 52 to 77) were included in the study. Peyronie's disease plaques were found in 35 men (3.67%). Eight hundred and forty-five (88.6%) were Caucasians. There was no significant statistical difference regarding age (P > 0.05). The presence of erectile dysfunction in the men with Peyronie's disease and without this condition, was 68.6% and 53.5%, respectively (P > 0.05). From this data we can conclude that the prevalence of Peyronie's disease is higher than in formerly reported studies. Further observations should be carried out in different communities and in other groups of patients in order to confirm our results.