Background: Patients with metabolic syndrome (MetS) are at increased risk for developing diabetes mellitus and cardiovascular disease. Limited information is available about the prevalence of MetS among Thai men and women. In this study we sought to estimate the prevalence of MetS among a population of patients receiving annual health exams. We also studied the relationship between MetS and elevated white blood cell (WBC) Count. Methods: This was a cross-sectional study of 1383 patients (375 men and 1008 women) who participated in annual health examinations at the Preventive Medicine Clinic of the King Chulalongkorn Memorial Hospital in Bangkok, Thailand, from July 1999 through February 2000. The presence of MetS was defined using the modified criteria of the National Cholesterol Education Program Adult Treatment Panel III. Results: Overall, the prevalence of the MetS was 12.8% and was more common among men than women (15.7% v 11.7%). Advanced age and elevated WBC counts were the only statistically significant risk factors of MetS in this population. The WBC count was statistically significantly correlated with high-density lipoprotein-cholesterol and triglyceride (P = .05). Men with highest WBC count (>= 7.50 X 10(3) cell/mu UL) had a 2.98-fold increased in risk of MetS (odds ratio 2.98. 95% confidence interval 1.29 to 6.87), as compared with men in the lowest quartile (< 5.40 X 10(3) cell/mu L). Among women, the risk of MetS increased across successive quartiles of WBC counts (1.00, 2.26, 2.88, and 4.30, with the lowest quartile as the referent group). Conclusions: In this study of Thai men and women receiving routine health examinations, MetS was found to be prevalent. In addition, WBC count (indicative of systemic chronic inflammation) is positively associated with MetS. (c) American Journal of Hypertension, Ltd.