Objective: To estimate the prevalence of environmental tobacco smoke (ETS) inside or outside the home among school-goingadolescents in Kampala, Uganda.Methods: Data from the Kampala Global Youth Tobacco Survey (GYTS) of 2002 was used. We estimated frequencies and proportionsof self reported exposure to ETS by the study participants. With logistic analysis, we assessed the association between ETS (outcome)in the home or outside the home and the following variables: sex; parental smoking status; and whether best friend was a smoker ornot.Results: Of the 2427 non-smoker teenagers who participated in this study, 52.8% were females, 17.9% were exposed to ETS at homewhile 48.7% were exposed to ETS outside of the home. The majority of the participants (65.8%) were in favour of banning smokingin public places such as in hotels, taxi, in schools, on playgrounds, in discos, markets, and shops. Compared to female participants,males were more likely to be exposed to ETS outside of the home (OR=1.21; 95% CI [1.02, 1.44]). Having parents and close friendswho smoked cigarettes was positively associated with exposure to ETS at home or outside of the home. Responders whose parentssmoked cigarettes were more than four times likely to be exposed to ETS at home than those whose parents were non-smokers (OR=4.88; 95% CI [3.76, 6.33]).Conclusion: Cultural factors may expose boys to ETS than girls. We also found that having parents who were smokers exposedadolescents to ETS outside the home and having best friends who smoked exposed adolescents to ETS. This may suggest thatadolescents who are exposed to ETS in one way may also be at risk of exposure through other means.