Metabolic syndrome was first proposed in 1988 and has been recognized as a powerful predictor for cardiovascular disease and diabetes. At the same time, white blood cell count (WBCC) was proposed to have significant correlation with metabolic syndrome (MS). In this study, we attempted to investigate the relationship between WBCC and components of metabolic syndrome in subjects in Taiwan with normal WBCC, no significant medical disease, and no medications known to affect the components of MS. We enrolled 1185 subjects with age > or = 40 years in 1997. These subjects participated in the annual health examination of the MJ Life Clinic. Subjects with abnormal WBCC (> 10x 10(9) cells/l), history of diabetes, hypertension or hyperlipidemia, or taking medications for these diseases or medications known to affect components of MS, were excluded. Because the menstrual cycle has an effect on the components of MS, we divided the subjects into three groups: male (M group, n = 576), old female (OF group, aged > or = 50 years, n = 307), and young female (YF group: aged < 50 years, n = 302). Each group was further divided into four quartiles according to WBCC (WBCC1 to WBCC4, from the lowest to highest WBCC). The body mass index (BMI) of YF was significantly lower than both M and OF. The diastolic blood pressure (DBP) and triglycerides (TG) were higher in M than YF. High-density lipoprotein cholesterol (HDLC) was lower in M compared to both YF and OF. When evaluating the metabolic components in different quartiles of WBCC in M, only WBCC1 had lower BMI and TG than WBCC4 after adjustment for age and BMI. For OF, the results were similar, the BMI of both WBCC1 and WBCC2 was lower than WBCC3 and TG of WBCC1 was lower than WBCC4. Finally, in YF, none of the BMI, blood pressure, FPG, HDLC, or TG was different in the four WBCC quartiles. The results of multiple regression between the WBCC and components of MS after adjustment for age and BMI were also evaluated. Significant correlations could only be noted in WBCC with BMI and TG in M and OF. In conclusion, in subjects with normal WBCC and no history of significant medical diseases, BMI and TG are significantly related to the levels of WBCC and are the two earliest components of MS to be noted, especially in males and post-menopausal females.