Two known isoquinoline alkaloids, (+)-chelidonine (1) and (-)-stylopine (2), were isolated from $CHCl_3$-soluble fraction of whole plants of Chelidonium majus L. var. asiaticum, and their structures were identified by spectroscopic methods and X-ray crystallographic analysis. Two isolates (1 and 2) were examined for their in vitro cytotoxic activities against five human cancer cell lines including DU-145 (prostate), MCF (breast), A549 (lung), HePG2 (liver), and HT-29 (colon) by sulphorhodamine B (SRB) assay.