Indoor tanning (IT) has been linked with psychiatric and addictive symptoms, and frequent tanning may indicate tanning dependence (addiction). The current study evaluated the effects of an IT episode on mood states and the association of these effects with psychiatric and addictive symptoms among young adult female indoor tanners. One-hundred thirty-nine female university students aged 18-25 years who had indoor tanned completed an online survey including the Positive and Negative Affects Scales and a standardized psychiatric interview (the MINI International Neuropsychiatric Interview) via telephone. Psychiatric and addictive symptoms were relatively common among these young adult female indoor tanners. Overall, participants reported significant decreases in both negative (upset, scared, irritable, nervous, jittery, afraid) and positive (feeling interested) mood states after their most recent tanning episode. Multivariable linear regression analyses showed that more frequent indoor tanning in the past month and symptoms of illicit drug use disorders were associated with decreases in negative mood, and symptoms of generalized anxiety disorder were associated with a decrease in feeling interested. In summary, indoor tanners report relatively high rates of psychiatric and substance use symptoms, including symptoms of tanning dependence, and indoor tanning appears to alter mood. Women with certain substance use and psychiatric characteristics may be more vulnerable to such mood changes after tanning indoors. Further research is needed to clarify the relationships among these variables.