Background: Depression is a psychological dysfunction that impairs health and quality of life. However, whether environmental tobacco smoke exposure (ETSE) is associated with depression is poorly understood. This study was designed to evaluate the association of ETSE with depression among non-smoking adults in the United States.Method: Using the 2015-2016 United States National Health and Nutrition Examination Survey (NHANES), we identified 2623 adults (females - 64.2%, males - 35.8%) who had never smoked and applied multivariable adjusted-logistic regression to determine the adjusted odds ratio (aOR) and 95% confidence interval (CI) at P < 0.05 for the association of ETSE with depression adjusting for relevant confounders.Results: Mean age of respondents was 46.5 ± 17.9 years, 23.5% reported ETSE, and 4.7% reported depression. Also, aORs for the association of ETSE with depression were 1.992 (1.987, 1.997) among females and 0.674 (0.670, 0.677) among males. When we examined the association by age groups, the aORs were 1.792 (1.787, 1.796) among young adults (< 60 years) and 1.146 (1.140, 1.152) among older adults (≥60 years).Conclusions: We found that ETSE was associated with higher odds of depression among females but not among males. [ABSTRACT FROM AUTHOR]