The study was renewed for one year in 1993 as a continuation and extension of the study of the association between occupational stress ('job strain', evaluated by the Karasek Job Content Survey) and hypertensive cardiovascular disease, evaluated principally by ambulatory blood pressure (ABP) and left ventricular mass index (LVMI). It was originally a case control study in which cases (hypertensive subjects) were found to be more likely to be exposed to job strain than normotensive controls, with an odds ratio of 2.75, and to have a greater LVMI. This effect was independent of other known risk factors for hypertension. It was extended as a prospective study of 314 men and women studied at 9 worksites during Waves of observation over five years. Preliminary results from Waves 1 and 2 showed a longitudinal association between persistent job strain and progressive elevation of ABP.