The cost-effectiveness of treating hypertension at the patient's place of work was compared in a randomized controlled trial with care delivered in a community. The average total cost per patient for worksite care in this 12-month study was not significantly different from that for regular care ($242.86 +/- 6.94 vs $211.34 +/- 18.66, mean +/- SEM). The worksite health system cost was significantly more expensive ($197.36 +/- 4.99 vs $129.33 +/- 13.34, p less than 0.001) but the patient cost was significantly less ($45.40 +/- 3.23 vs $82.00 +/- 6.20, p less than 0.01). The mean reduction in diastolic blood pressure (BP) at the year-end assessment was significantly greater in the worksite group (12.1 +/- 0.6 vs 6.5 +/- 0.6 mm Hg, p less than 0.001). The incremental cost-effectiveness ratio of $5.63 per mm Hg for worksite care was less than the base cost-effectiveness ratio of $32.51 per mm Hg for regular care, indicating that the worksite program was substantially more cost-effective. Our findings support health policies that favor allocating resources to work-based hypertension treatment programs for the target group identified in this study.