Antioxidant, antitumor and anticarcinogenic activity of gossypin (3,5,8,3',4'-pentahydroxy-7-O glucosyl flavone) was carried out. The compound needed for 50% inhibition of superoxide, hydroxyl and nitric oxide radicals was 3 microg/ml, 41 microg/ml and 12 microg/ml, respectively. Gossypin also impart 50% inhibition at concentrations 37 microg/ml and 43 microg/ml, respectively for in vitro lipid peroxidation. The compound shows IC50 of 30 microM, 42.5 microM and 45.1 microM concentrations in L 929, HT 29 and K 562 cell lines in 72 hrs MTT assay. The compound shows a zone of inhibition of 8 mm in topo I and topo II inhibition assay in Saccharomyces ceriviseae mutant cultures. It reduces the tumor burden in solid tumor harboring animals (p < 0.001) and effectively inhibits the formation of new blood vessels on tumor mass. 20 mg/kg b.wt of gossypin increase the life span of ascites tumor harboring animals (100%) and (164.7%) respectively by oral and intraperitoneal administration of the drug. Gossypin reduced the incidence of papilloma formation and papilloma/mouse in DMBA/ croton oil induced skin papilloma.