Abstract: Objective To assess the prevalence of isolated systolic hypertension（ISH）and its associated risk factors among the middle-aged and elderly adults in Chengdu area,and further to provide a theoretical basis for the prevention and treatment of hypertension. Methods In 2008,a total of 5205middle-aged and elderly adults aged 40-79 years were enrolled from Chengdu area using a stratified cluster sampling method. Data on blood pressures and other clinical characteristics were collected by more than 30 healthy workers who had undergone unified trainings. The prevalence of ISH was recorded,and potential risk factors were analyzed. Results Overall,the prevalence of ISH was 16.64%in the rural and urban areas of Chengdu,and its standardized prevalence was 15.87%. The prevalence of ISH was 17.18%in the urban areas of Chengdu,which was significantly higher than that（14.23%）in the rural areas（P＜0.01）. The prevalence of ISH was respectively 16.09% and 16.99% in males and females,the difference being nonsignificant（P=0.40）. There was an increasing prevalence with the increase of age. Stepwise Logistic regression analyses indicated that for males age,salty food and abdominal obesity were associated with ISH risk,while for females risk factors included age,menopause,overweight or obesity and abdominal obesity and protective factors included high education degree and appropriate exercise. Conclusion There was a high prevalence of ISH among the middle-aged and elderly adults in Chengdu area,and this prevalence was closely related with aging.It will be of importance to control body waist and weight,reduce salt intake and increase moderate exercise to prevent ISH in this area.