Objective: The purpose of this study was to examine the association between asthma diagnosis and obesity among adolescents exposed to environmental tobacco smoke (ETS). Methods: The sample included 28 807 adolescents (13-17 years old) from the National Survey of Children's Health (NSCH) (2011-2012). Study design: The NSCH is a US cross-sectional telephone survey that included at least one child between the ages of 0 and 17 years residing at a household during the time of the interview. Descriptive statistics were used to describe sample characteristics and assess the prevalence of asthma among adolescents with obesity exposed to ETS. Logistic regression models were built to assess the effect of obesity on asthma diagnosis within the context of ETS exposure. Results: The prevalence of asthma among adolescents was 10.4% and the obesity was 13.2%. Adolescents with obesity exposed to ETS within the home were significantly (p < 0.05) more likely to have an asthma diagnosis (23%) compared with non-obese (10.9%) residing in similar households. Adjusted odds ratios showed that adolescents with obesity were 2.07 (95% CI, 1.15, 3.70) times more likely to have asthma if they were exposed to ETS inside their homes. Conclusion: The findings indicate that adolescents with obesity are more likely to be diagnosed with asthma if they are exposed to ETS in the household. It is important that the association between obesity and asthma is examined within the context of environmental risk factors in future studies, as this may shed some light to underlying mechanisms between these two serious public health issues.