Background: Dysregulated bile acid (BA) metabolism has been linked to steatosis, inflammation, and fibrosis in nonalcoholic fatty liver disease (NAFLD).Aim: To determine whether circulating BA levels accurately stage liver fibrosis in NAFLD. Methods:We recruited 550 Chinese adults with biopsy-proven NAFLD and varying levels of fibrosis. Ultra-performance liquid chromatography coupled with tandem mass spectrometry was performed to quantify 38 serum BAs.Results: Compared to those without fibrosis, patients with mild fibrosis (stage F1) had significantly higher levels of secondary BAs, and increased diastolic blood pressure (DBP), alanine aminotransferase (ALT), body mass index, and waist circumstance (WC). The combination of serum BAs with WC, DBP, ALT, or Homeostatic Model