The hypothesis that increased blood pressure reactivity to stress is an early risk marker of hypertension was tested in a 1994 follow-up of the 1974 to 1978 Air Traffic Controller Health Change Study sample. Assessments in 1974 to 1978 included physical examinations and recordings (every 20 minutes for 5 hours) of both workload (planes within controller airspace) and blood pressure reactivity. Individual differences in reactivity were used to predict 1994 self-report of ever having been told by a physician to take antihypertensive medication, assessed in a telephone survey of 218 respondents who were normotensive or stage 1 hypertensive in 1974 to 1978. Each SD increase in baseline systolic reactivity was associated with a 1.7 (p <.019) increase in the relative-odds of 1994 hypertension, after controlling for age, body mass index, and clinic systolic and diastolic blood pressure at clinical examination, with effects comparable for baseline normotensives and stage 1 hypertensives. A 20-year follow-up of originally normotensive and stage I hypertensive workers suggests that increased systolic blood pressure reactivity to work stress is associated with long-term risk of hypertension.