Pathogenesis of erectile dysfunction (ED) is related to endothelial dysfunction and therefore associated with cardiovascular risk factors. Patients with a combination of risk factors, as in metabolic syndrome, are thus likely to have an increased risk of developing endothelial and ED. The angiotensin receptor antagonist irbesartan has been shown to improve endothelial function in cardiovascular high-risk patients, which suggests a beneficial effect of treatment with irbesartan on ED. The aim of the present study was to determine the influence of irbesartan on ED in patients with a metabolic syndrome. A total of 1069 consecutive hypertensive patients with a metabolic syndrome from the Documentation of hypertension and metabolic syndrome in patients with Irbesartan Treatment survey were included. Patients were treated with irbesartan or the combination of irbesartan/hydrochlorothiazide for 6 months. ED was assessed using the international index of erectile function. The Cologne Evaluation Questionnaire of Erectile Dysfunction served as a control. Erectile function increased significantly (P<0.0001) after 6 months of treatment with irbesartan, irrespective of dosage and independent of additional treatment with hydrochlorothiazide. Prevalence of ED declined to 63.7% from 78.5% at baseline, along with a significant increase in orgasmic function (P<0.001) and intercourse satisfaction (P<0.001). Treatment with irbesartan alone, as well as in combination with hydrochlorothiazide is associated with an improvement of sexual desire, frequency of sexual contacts and erectile function in hypertensive patients with the metabolic syndrome. These results suggest a beneficial role of angiotensin receptor antagonists in the treatment of metabolic syndrome, and ED.