Abstract: AIM:To investigate P-wave dispersion (PWD) in patients with metabolic syndrome (MetS). METHODS: Sixty-two patients with MetS ［34 males, 28 females; mean age (55.2±8.2) years］ and 58 control subjects without MetS (30 males, 28 females; mean age 54.6±8.7 years) were recruited. MetS diagnosis was based on the International Diabetes Federation MetS criteria and central obesity was evaluated by waist circumference (≥90 cm in male and ≥80 cm in females) according to the epidemiological data from Shanghai and Hong Kong in China. A 12-lead electrocardiogram was recorded for each subject. The difference between the maximum and minimum P-wave duration was calculated and defined as PWD. Echocardiographic examination was also performed for each subject. RESULTS: Maximum P-wave duration and PWD were significantly higher in patients with MetS compared with control subjects ［maximum P-wave duration (112±8) msec vs.(98±9) msec, PWD (37±7) msec vs.(23±5) msec, P<0.01 for both］. However, no statistically significant difference in the minimum P-wave duration was found between the groups. In addition, PWD was positively correlated with age, body mass index, waist circumference, systolic and diastolic blood pressure, total cholesterol and triglyceride levels, but was negatively correlated with high-density lipoprotein cholesterol level. Multiple linear regression analysis showed that age (β=0.394, P<0.01,) BMI (β=0.22, P=0.002), waist circumference (β=0.165, P=0.02), systolic blood pressure (β=0.166, P=0.012), total cholesterol (β=0.195, P=0.009) and triglyceride level (β=0.227, P=0.004) were independent risk factors of PWD. CONCLUSION: Patients with MetS have higher PWD, which may be responsible for increased risk for atrial fibrillation.