We sought to determine whether serum concentrations of fibroblast growth factor 19 (FGF19) – an ileum-derived enterokine which plays a role in the control of glucose and lipid homeostasis – are altered in patients with biopsy-proven nonalcoholic fatty liver disease (NAFLD).Serum levels of FGF19 were measured using enzyme-linked immunosorbent assay in 91 patients with biopsy-proven NAFLD and 74 controls.FGF19 levels were significantly lower in patients with biopsy-proven NAFLD (median: 130pg/mL) than in controls (median: 210pg/mL, P<0.001). Serum FGF19 levels were significantly but modestly associated with hepatocyte ballooning scores in univariate analysis (r=−0.25, P<0.05) but not after adjustment for potential confounders (β=−0.18; t=1.78, P=0.08).This pilot study suggests that serum FGF19 levels are decreased in patients with NAFLD but are not independently associated with liver histology findings.