The aim of this study was to investigate the effect of Moutan Cortex on acetaminophen (AAP)-induced toxicity in human Chang liver cells. Cells were incubated with AAP (0—30 mM) to evaluate the drug’s ability to reduce cytoviability. For the cells treated with 10, 20 and 30 mM AAP, LDH leakage was 39.8%, 49.0% and 57.6%, respectively. Administration of Moutan Cortex reduced cytotoxicity in a dose-dependent manner. Glutathione (GSH) concentration in human liver cells decreased significantly after exposure to 20 (p<0.05) and 30 mM (p<0.01) AAP, and increased (p<0.05) if incubated with AAP and Moutan Cortex. The ability of AAP to inhibit mitochondrial function and its counteraction by Moutan Cortex was also evaluated. Moutan Cortex showed dose-dependent increases in MTT metabolism and ATP levels in AAP-treated cells. The DNA content of AAP-treated cells increased with the treatment of Moutan Cortex. These observations demonstrate that Moutan Cortex may significantly attenuate AAP-induced toxicity. It can be considered a cytoprotective agent in this in vitro model of drug toxicity.