Extracts of various samples of the crude drug prepared from Atractylodes rhizomes exhibited antihepatotoxic activity by in vitro assay methods using carbon tetrachloride- and galactosamine-induced cytotoxicity in primary cultured rat hepatocytes. The main sesquiterpenoid components were subjected to screening by these methods to reveal that atractylon, beta-eudesmol, and hinesol exerted significant liver-protective effects. Some analogs were also assayed.