FGF19 and depressive disorder: <h4>Objective</h4>This study aimed to examine the relationship between fibroblast growth factor 19 (FGF19) and depressive symptoms, measured by Beck's Depression Inventory (BDI) scores and investigate the moderating role of smoking.<h4>Methods</h4>This study involved 156 Chinese adult males (78 smokers and 78 non-smokers) from September 2014 to January 2016.