With China's rapid economic development, the disease burden may have changed in the country. We studied the major causes of death and modifiable risk factors in a nationally representative cohort of 169,871 men and women 40 years of age and older in China. Baseline data on the participants' demographic characteristics, medical history, lifestyle-related risk factors, blood pressure, and body weight were obtained in 1991 with the use of a standard protocol. The follow-up evaluation was conducted in 1999 and 2000, with a follow-up rate of 93.4 percent. We documented 20,033 deaths in 1,239,191 person-years of follow-up. The mortality from all causes was 1480.1 per 100,000 person-years among men and 1190.2 per 100,000 person-years among women. The five leading causes of death were malignant neoplasms (mortality, 374.1 per 100,000 person-years), diseases of the heart (319.1), cerebrovascular disease (310.5), accidents (54.0), and infectious diseases (50.5) among men and diseases of the heart (268.5), cerebrovascular disease (242.3), malignant neoplasms (214.1), pneumonia and influenza (45.9), and infectious diseases (35.3) among women. The multivariate-adjusted relative risk of death and the population attributable risk for preventable risk factors were as follows: hypertension, 1.48 (95 percent confidence interval, 1.44 to 1.53) and 11.7 percent, respectively; cigarette smoking, 1.23 (95 percent confidence interval, 1.18 to 1.27) and 7.9 percent; physical inactivity, 1.20 (95 percent confidence interval, 1.16 to 1.24) and 6.8 percent; and underweight (body-mass index [the weight in kilograms divided by the square of the height in meters] below 18.5), 1.47 (95 percent confidence interval, 1.42 to 1.53) and 5.2 percent. Vascular disease and cancer have become the leading causes of death among Chinese adults. Our findings suggest that control of hypertension, smoking cessation, increased physical activity, and improved nutrition should be important strategies for reducing the burden of premature death among adults in China. Copyright 2005 Massachusetts Medical Society.