The influence of occupational category (OC) on the prevalence of hypertension (HT) and cardiovascular risk factors and on their management was studied in Paris in a general population and in a series of patients followed up in two university hospital hypertension clinics. Three OCs were defined as follows: high executives and members of liberal professions middle executives and clerks and manual workers. In the general population, the prevalence of HT was positively associated with OC, and ranged from 12.8% (1) to 19.3% (3). Body Mass Index (BMI) and tobacco and alcohol consumption were higher in category 3. Exposure to noise and assembly-line work raised blood pressure. Of the hypertensive subjects, 60% were aware of their illness, independently of OC, but the percentage of treated hypertensive subjects at examination and their compliance with treatment were significantly and negatively correlated with OC. In the hypertension departments, more category 1 and 2 patients were examined than expected for a theoretical French population of similar sex, age and geographical distribution. By contrast, clerks and manual workers were under-represented. BMI was higher in OC 3 than in OC 1, in both sexes. Cigarette consumption was higher in OC 1 than in OC 3 in males only. Permanent teaching staff members examined more people from OC 1 than the other physicians did. Drop-out rates at 1, 2 and 3 years were higher in OC 3 than OC 1. The problems of compliance with antihypertensive treatment were more frequent in OC 3 patients than in those in the other categories.(ABSTRACT TRUNCATED AT 250 WORDS)