The influence of a systematic survey and follow-up of blood pressure in a population sample was assessed by a subsequent survey performed an average of 40 months later. A subsample of 746 men, originally ages 35-57 years, was randomly selected for telephone follow-up, while blood pressure was remeasured in 133 (17% of the subsample). These were drawn from 6779 men who had a diastolic blood pressure (DBP) ≥ 90 mm Hg, the average of the second two measurements of three at the initial survey. Ninety percent of the men in the telephone survey reported that they had visited their physician or medical-care source. Of these visits, 70% were for consideration of blood pressure, and in 36% this visit was directly attributed to the screen. At follow-up, 52.8% were taking antihypertensive medication and in 61% of this group the medication was started after the initial screen. Follow-up revealed DBP reduced by 8.7% in the group not treated with antihypertensive agents either before of after the initial survey, by 13.4% in the group on treatment before the survey and by 17.7% in the group started on therapy after the survey. Although lack of a suitable comparison group is a limitation, these findings in a population-based cohort strongly suggest that systematic blood pressure screening, combined with effective immediate referral, may be associated with an important effect on blood pressure control in the community.