Objective:To investigate the associations of major depressive disorder with coronary heart disease (CHD)and stroke in Chinese adults aged 30 -79 years.Methods:In 2004 -2008,China Ka-doorie Biobank was conducted in 1 0 geographically defined regions (5 urban and 5 rural)of China.A to-tal number of 51 2 891 participants aged 30 -79 years were recruited in the baseline survey.A laptop-based electronic questionnaire was administrated face-to-face by trained health workers,collecting the general demographic and socio-economic status,dietary and other lifestyle behaviours (e.g.smoking,al-cohol drinking,physical activity),medical history and family history of common chronic diseases.Major depressive episodes (MDE)in the past 1 2 months were assessed with the World Health Organization composite international diagnostic interview-short form (CIDI-SF).The physical measurements included the heights and weights,which were used to calculate the body mass indexes (BMI).Chi squared and t test were used to compare the differences in participants characteristics according to their major depressive disorder.Logistic models were employed to estimate the odds ratios (OR)and 95% CI of their major de-pressive disorder with prevalent coronary heart disease and stroke.Results:Among the 51 2 891 partici-pants,3 281 (0.6%)showed an MDE in the preceding 1 2 months,1 5 472 (3.0%)reported prevalent CHD,and 8 884 (1 .7%)reported prevalent stroke.Major depressive disorder was significantly associa-ted with an increased risk of CHD and risk of stroke.Age-and gender-adjusted ORs (95% CI)were 1 . 80 (1 .53 -2.1 2)for CHD and 2.53 (2.09 -3.05)for stroke.The associations were significant after further adjustment for potential confounders,such as other socio-demographic status,smoking,alcohol drinking,physical activity,and BMI,prevalent hypertension,diabetes as well as family history of cardio-vascular diseases (OR =1 .83,95% CI =1 .54 -2.1 8 for CHD;OR =2.1 9,95% CI =1 .79 -2.69 for stroke).Moreover,gender significantly interacted with MDE on prevalent stroke (P for multiplicative in-teraction =0.01 3).The men with an MDE in the past 1 2 months had the highest risk of stroke in the joint analyses of gender and depression disorder (OR =5.02,95% CI =3.70 -6.82).Conclusion:The findings from this large cross-sectional study suggest that the presence of MDE is a risk factor for both CHD and stroke in Chinese adults aged 30 -79 years,but further prospective studies are warranted to validate the results.