OBJECTIVE: Many population studies worldwide have shown high prevalence of erect ile dysfunction, a condition that increases dramatically with age. Other risk factors are also well known such as diabetes and arteriosclerosis. The aim was to study the prevalence and risk factors of erectile dysfunction among Icelandic men. MATERIAL AND METHODS: The participants were 4000 men age 45-75 year old randomly chosen from the Icelandic National Registry. They received a 27 item questionnaire to access the degree of erectile dysfunction using the 5 question International Index of Erectile Function (IEEF), and also other aspects of sexual health, medication and concomitant diseases. RESULTS: The response rate was 40.8%. The overall prevalence of erectile dysfunction was 35.5%. The condition was significantly more prevalent in the older age group (65-75) compared to the younger group (45-55), 21.6% vs 62.3% respectively. Other significant risk factors were smoking, diabetes, high cholesterol, hypertension, depression and anxiety disorder. Sexual activity and interest is high in all age groups. Physicians rarely take the initiative of asking men about sexual dysfunction. Only about 24% of males with erectile dysfunction have received some treatment. CONCLUSION: This first population based study among Icelandic men shows a high prevalence of erectile dysfunction and is in accordance with similar studies in other counties. Significant risk factors are the same as are well known for cardiovascular diseases. Thus preventive measures should be the same for both conditions.