Certain physiopathological features that differentiate essential arterial hypertension in normal weight and obese patients are recalled. The results of a retrospective study carried out in 293 hypertensive patients admitted to the Clinic in recent years are reported with a view to evaluating the prevalence of certain parameters (ischaemic cardiopathy, left ventricular hypertrophy, renal, vasculo-cerebral and retinal impairment) in patients subdivided into two groups: normal weight and obese. The study showed in the first group a higher prevalence of signs of ischaemic cardiopathy; in the second a higher prevalence of left ventricular hypertrophy. This difference is accentuated in the subgroup of smokers as regards ischaemic cardiopathy and in non-smokers as regards left ventricular hypertrophy. The possible explanations for this different behaviour are discussed.