OBJECTIVES: This study was conducted to develop a worksite-based, post-examination, health care management system for continuous and systematic management of workers with hypertension, diabetes mellitus, hyperlipidemia, and abnormal LFT detected by periodic health examination and to assess the effectiveness such a system as an intervention study. METHODS: Study subjects were selected from workers with hypertension, diabetes mellitus, hyperlipidemia, and abnormal LFT according to the selection criteria. The intervention group, but not the control group, received medical treatment of disease, follow up examination, and health education which consisted of information about the disease and the importance of life-style modification through periodic interview using the resources of occupational health service center in the worksite. To assess the effectiveness of this system, we compared follow up examination data from the intervention group with periodic examination data from the worksite control group. RESULTS: In the intervention group a significant reduction trend was recorded for systolic and diastolic blood pressure, fasting blood sugar, postprandial 2 hour glucose, total cholesterol, triglyceride, LDL-cholesterol, AST, ALT, and gamma-GTP, and a rising trend for HDL-cholesterol. Significant group differences ware recorded for fasting blood sugar, postprandial 2 hour glucose, total cholesterol, AST, and ALT. CONCLUSIONS: The worksite-based, post-examination, health care management system was effective for the continuous and systematic management of workers who had abnormal findings detected by periodic health examination.