Introduction: Previous studies exploring associations of physical inactivity, obesity, and out-of-pocket expenditure (OOPE) mainly used traditional linear regression, and little is known about the effect of both physical inactivity and obesity on OOPE across the percentile distribution. This study aims to assess the effects of physical inactivity and obesity on OOPE in China using a quantile regression approach. Methods: Study participants included 10,687 respondents aged 45 years and older from the recent wave of the China Health and Retirement ...