Hypertension remains a major cause of cardiovascular morbidity in Belgium. Information on the prevalence of hypertension in the working population is desirable. A worksite study of hypertension prevalence was carried out in Belgium where 3472 individuals were screened for 1 week. The result was that high blood pressure (> or = 140/90 mm Hg) was identified in approximately one-third of the men and one-quarter of the women even though the majority of subjects had no recorded history of hypertension. Associations were identified between age and systolic blood pressure and, in men, between systolic blood pressure and alcohol consumption. Most participants in the survey were unaware of their serum cholesterol level. The results of this survey suggest that a large proportion of subjects with high blood pressure in the Belgian working population remain unidentified and indicate a lack of awareness about other cardiovascular risk factors.