The prevalence of and risk factors for hypertension were determined among habitants in the European side of Istanbul who are 25 years and older. Eight administrative districts were selected with the method of simple random sampling. The participants were selected through systematic calling from address lists. Between 17 and 22 June 2002, the questionnaires were applied to the participants in a face-to-face interview; then arterial blood pressures, body weights and heights of the participants were measured. Of 423 adults participating in the study, 35.5% were hypertensive; 35.9% were obese, 27.9% were overweight and 2.1% were underweight. Risk factors for hypertension such as age, gender, educational status, social security, family history of hypertension and cardiovascular disease, medical history of diabetes and congestive heart failure, smoking and alcohol use, and body mass index in the hypertensive and non-hypertensive groups were investigated by means of logistic regression analysis. Age [odds ratio (OR): 5.20, 95% confidence interval (CI): 2.18-12.40], body mass index (OR: 2.22, 95% CI: 1.57-3.16) and smoking (OR: 0.72, 95% CI: 0.55-0.95) were found to be correlated with hypertension. The results showed that the prevalence of hypertension was high in Istanbul, and obesity, being overweight and advanced age were the risk factors for hypertension.