Aim To investigate the factors causing insulin resistance in subjects with the metabolic syndrome (MS). Methods 1261 administrative officers aged 20～62 years were studied for the MS using Adult Treatment Panel Ⅲ (ATP Ⅲ) criteria but with a modified waist circumference appropriate for Chinese (men>90 cm,women>80 cm). Insulin resistance was calculated using the Homeostasis Model Assessment (HOMA) equation. Results The prevalence of the MS was 11.4% and 10.3% in men and women,respectively. There was no significant difference in prevalence of the MS between men and women. HOMA-IR index of the MS group significantly higher than that of control in both sexes. Multiple stepwise regression suggested fasting plasma glucose level,triglyceride level,and waist circumference significantly associated with HOMA-IR among components of the MS. Conclusion The factors causing insulin resistance in subjects with the MS were fasting plasma glucose level,triglyceride level,and waist circumference.