An association of obesity and hypertension is well recognised and there is a direct positive relationship between body weight or body mass index (BMI) and blood pressure (BP), although the mechanisms responsible for weight-related increases of BP are still unknown. Obesity does appear to be an independent risk factor for premature mortality, especially when it is associated with other risk factors such as hyperinsulinemia and glucose intolerance (or diabetes), hyperlipidemia, and hypertension. However, there are differences among racial and ethnic subgroups. The aim of our study was the investigation of the prevalence of obesity and its severity among Greek hypertensive patients in comparison to normotensive controls. We have studied a large enough sample of Greek hypertensives consisting of 1101 patients (504 male/597 female, 23-85 years of age) and 242 normotensive controls (136 male/106 female, 23-75 years of age). In all patients and normotensive controls BMI (ie weight/height in 2mm) was measured, as well as the waist-to-hip (W/H) ratio. A BMI of less than 27 was accepted as normal, a BMI of 27-32 as indicating mild to moderate obesity, a BMI of 32-37 as an index of severe obesity, and a BMI > 37 as a measure of very severe obesity. Obesity in hypertensive patients was more frequent than in normotensive controls (62.5% vs 54.2%, P = 0.024), and hypertensive women were more commonly obese than hypertensive men (67.16% vs 56.8%, P = 0.002). Severe and very severe obesity was more common in hypertensive women than in men (20.7% vs 9.68%, P < 0.001, and 8.1% vs 0.52%, P < 0.0001, respectively), although obesity of severe and very severe degree was equally found in hypertensives and normotensives of both sexes. BMI of all hypertensives was significantly greater in comparison to that of normotensives (30.13 +/- 0.44 vs 26.74 +/- 0.76, mean +/- s.e., P < 0.0001); W/H ratio of hypertensives was significantly greater than that of normotensives, indicating more frequent central obesity in hypertensives. We conclude that obesity in Greek hypertensive patients is more frequent than in normotensive controls, while hypertensive women have more severe obesity than hypertensive men, and are more frequently obese than men.