Plasma 25-OH-D levels of normotensive and hypertensive subjects living in a highly industrial and in a nonindustrial area, were estimated. Significantly higher values were found in normotensive subjects than in hypertensive patients. Severity of arterial hypertension was not related to plasma 25-OH-D. Both groups of subjects (normotensive and hypertensive) living in the industrial area with high air pollution had lower 25-OH-D concentrations than those living in the nonindustrial region. Data presented in this paper suggest that antihypertensive treatment by pharmacologic agents exerts a depressive effect on plasma 25-OH-D level.