Exposure to second-hand tobacco smoke is a public health problem in countries with high prevalence of active smoking such as Pakistan. However, few studies have assessed the prevalence and risk factors for exposure to second-hand tobacco smoke. To estimate the prevalence and factors associated with exposure to second-hand tobacco smoke in Pakistan. This study used data from the 2017-2018 Pakistan Demographic and Health Survey to calculate the prevalence and determinants of second-hand tobacco smoke exposure. Sociodemographic characteristics, family size and exposure to media by the respondents were the independent variables. The chi-square test and logistic regression analyses were used to evaluate the relationship between exposure to second-hand tobacco smoke and the independent variables.hy9. The survey included 61 940 adults, of which 30 027 (48.5%) were males and 31 913 (51.5%) females. The overall prevalence of exposure to second-hand tobacco smoke was 34.3%: 35.6% among males and 33.2% among females. Higher education level and rural residence were significantly positively associated with exposure to second-hand tobacco smoke among both sexes. Having a radio was inversely associated with exposure while having a television was positively associated with exposure among both sexes. Large family size was inversely associated with exposure. Currently and previously married females had significantly greater risk of exposure than never-married females. Tailored health interventions and policies are needed that target populations at high-risk of exposure to second-hand tobacco smoke. Strict smoking bans in public places should be implemented to limit exposure to second-hand tobacco smoke in Pakistan.