Objective: Previous study conducted by the Turkish Society of Andrology in 1999 reported the prevalence oferectile dysfunction (ED) as 69.2% in men of ≥40 years of age, using a single-item non-validated question. Thisrate seemed to be higher compared to the studies reported worldwide. So, there was a need to carry out anotherepidemiological study by using validated questionnaires. Our aim was to investigate ED prevalence, severity,and its correlates in men aged ≥40 years using validated tools.Material and methods: This cross-sectional, observational, population-based field survey was carried outin randomly selected males of ≥40 years from 19 provinces of Turkey. All participant completed a surveyincluded with socio-demographic and socio-economic characteristics, medical and sexual history, associatedphysical and medical comorbidities. Erectile function was assessed by the International Index of Erectile Function(IIEF) questionnaire based on a total score of 30. The prevalence of ED, its severity and correlates in menaged ≥40 years were determined for main outcome measures. Data sets were statistically compared and p<0.05was considered as significant.Results: Median age of 2.760 males was 54.2 years. The median prevalence of ED was calculated as 33%among all males of ≥40 years of age. When subjects were stratified by age; median ED prevalence rates were17% for 40–49 years, 35.5% for 50–59 years, 68.8% for 60–69 years, and 82.9% for ≥70 years. Among all EDmen, 76.9% reported mild, 16.3% moderate, and 5.7% severe ED. At logistic regression analyses; age, diabetes,hypertension, atherosclerosis, dyslipidemia, lower urinary tract symptoms, educational status and monthlyincome were found to be independent risk factors for having ED.Conclusion: This population-based survey in Turkish men of ≥40 years of age reported the prevalence of EDas 33%. Besides, this study reported age as the main predictor for presence and severity of ED