Stellera chamaejasme has been used as a therapeutic plant for treatment of various inflammatory diseases and solid tumors. Our study was particularly interested in the differentiation inducing activity of the aerial parts of S.chamaejasme using human chronic leukemia cell line K562. The ethanol extract has been shown to be highly cytotoxic against K562 cells at >0.008% (v/v) doses. Cell cycle arrest at G(0)/G(1) phase, not detectable DNA fragmentation as well as positive staining with acridine orange and expression of beclin-1 protein in the treated cells led as to detect autophagic cell death during the plant extract treatment of K562 cells. Moreover, differentiation marker CD11b was also expressed in the treated cells. (C) 2010, The Society for Biotechnology, Japan. All rights reserved.