This is a multicenter cohort study on osteoporosis in six cities of China which locate in the east, south, north, west, middle of China respectively. At least 3000 middle-aged and elderly permanent residents (women aged from 45 to 79, and men aged from 50 to 79) in every city were enrolled. Residents with severe mental diseases, physical diseases or acute infectious diseases who could not cooperate with the survey as well as lactating or pregnant women were excluded. All the enrolled residents who signed informed consent will finish questionnaire including demographic characteristics, history of smoking, alcohol drinking, falls and fracture, family, chronic diseases and medicine,diary and physical practice. Osteoporosis risk, health status (EQ-5D) and constitution of traditional Chinese medicine (TCM) will be evaluated. Fasting blood tests, bone mineral density and physical examinations (height, weight, waist circumference, hip circumference,grip,sit-to-stand test, tongue coating and pulse) will be performed at enrollment and every two years after enrollment. DNA of blood cells will be preserved.