Background: The association between obesity and depression remains equivocal. The aims of this study were to examine the association between body mass index (BMI) and depressive symptoms in the Chinese adult population. Methods: In this study, data from the Health Promotion Knowledge, Attitudes, and Performance Survey, conducted in 2002 among 20,385 Taiwanese adults (aged 18-64 years), were used. Depressive symptoms were assessed by the Taiwanese Depression Questionnaire (cut off point 19). Weight status was categorized as underweight (BMI