Polygonum multiflorum, called Heshouwu in China, is a traditional Chinese medicine used to treat various diseases. However, the administration of P. multiflorum (PM) and P. multiflorum Praeparata (PMP) causes numerous adverse effects. This study sought to analyze the toxic components of PM using ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS), and their hepatotoxicity in L02 human liver cells. Toxicity was evaluated by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), lactate dehydrogenase (LDH) leakage, and liver enzyme secretion (aspartate aminotransferase [AST] and alanine aminotransferase [ALT]) assays. Furthermore, UPLC-Q-TOF/MS, Progenesis QI, and Makerlynx XS software analyses were used to differentiate extracts and analyze the toxic components. The order of toxicity was P. multiflorum ethanol extract (PME) > P. multiflorum water extract (PMW) > P. multiflorum Praeparata ethanol extract (PMPE) > P. multiflorum Praeparata water extract (PMPW), which was determined by KIT assay, LDH leakage, and liver enzyme secretion levels. The analysis methods suggest that PM toxicity may be associated with anthraquinone, emodin-O-(malonyl)-hex, emodin-O-glc, emodin, emodin-8-O-glc, emodin-O-(acetyl)-hex, and emodin-O-hex-sulphate. The toxic mechanisms.a these components require further study. (C) 2015 Elsevier B.V. All rights reserved.