The chloroform and hexane fractions and their sub-fractions of Polygonum bistorta (Polygonaceae) were evaluated for their cytotoxic activity against P338 (Murine lymphocytic leukaemia), HepG2 (Hepatocellular carcinoma), J82 (Bladder transitional carcinoma), HL60 (Human leukaemia), MCF7 (Human breast cancer) and LL2 (Lewis lung carcinoma) cancer cell lines in culture. Both the chloroform and hexane fractions and a few of their sub-fractions showed moderate to very good activity against P388, HL60 and LL2 cancer cell lines. Both active and non-active fractions were further investigated for their chemical constituents. A total of nine compounds, viz. 24(E)-ethylidenecycloartanone (1), 24(E)-ethylidenecycloartan-3 α-ol (2), cycloartane-3,24-dione (3), 24-methylenecycloartanone (4), friedelin (5), 3 -β friedelinol (6), β -sitosterol (7), γ-sitosterol (8) and β-sitosterone (9) were isolated. One of the pure compounds, 24(E)- ethylidenecycloartanone 1, which was obtained in sufficient quantity, was tested for its cytotoxicity against P388, LL2, HL60 and WEHI164 (Murine fibrosarcoma) cancer cell lines but was found to have no activity even at a concentration of 100 μg/mL.