The investigations carried out made possible an estimation of the share the group at risk for arterial hypertension has in the organized urban population. It was found that most men and women aged between 25 and 49 years (64.9%) are at risk for later developing arterial hypertension, risk determined by the limit values of blood pressure (in 7.7% of the normotensives), tachycardia (in 15.9%), presence of this disease in the parents (33.5%) or episodes of transient hypertension in the past (32%). Overweight, an important risk factor for hypertension, was found in 11.5% of the individuals with normal blood pressure values and the increased sodium excretion in 27%. The primary prophylaxis of hypertension should include large numbers of individuals, new methods and forms for drawing the population into such programs being needed.