OBJECTIVES: This study was performed to estimate the prevalence and possible risk factors of the metabolic syndrome in steel-mill workers, and to evaluate the relation between gamma-glutamyltransferase (gamma-GTP) and the metabolic syndrome. METHODS: The study subjects comprised 1,604 male steel-mill workers. The indices of metabolic syndrome, such as BMI, triglyceride, HDL-cholesterol, blood pressure, fasting glucose, and gamma-GTP were analyzed in each subject. We collected information about demographic characteristics, behavioral patterns, such as alcohol drinking, smoking, and exercise, and family medical history through a self-administered questionnaire. Statistical analysis was done by using the chi-square test, Mantel-Haenszel trend test and logistic regression model. RESULTS: The crude and age-adjusted prevalences of the metabolic syndrome were 21.3% and 15.5%, respectively, in the steel-mill workers. Age (OR: 1.063, 95% CI: 1.033-1.094), alcohol drinking (OR: 1.657, 95% CI: 1.175-2.337) and smoking (OR: 1.359, 95% CI: 1.017-1.816) were risk factors for the metabolic syndrome. Meanwhile, shift work showed a significant relation with hypertension (OR: 1.329, 95% CI: 1.038-1.700), but not with other metabolic syndrome components. However, tenure, exercise and family medical history were not significant factors for the metabolic syndrome in this study. The risk ratio of the metabolic syndrome (OR: 3.345, 95 % CI: 2.534-4.416) and its components, such as obesity, hypertriglyceridemia, hypertension and hyperglycemia, were higher in the high gamma-GTP group (> or =63 IU/ liter) than in the controls (<63 IU/liter). CONCLUSIONS: These results confirm the need for health education to control the metabolic syndrome by improving behavioral patterns, such as alcohol drinking and smoking, in factory workers. In addition, it is suggested that gamma-GTP might be a useful candidate in screening for the metabolic syndrome.