Gossypin is a glucosyl flavone obtained from the flowers of Hibiscus pitifolius (Malvaceace). It has potent analgesic and antiinflammatoryactivity. It has shown cytotoxic activity when tested against human lung adrenocarcinoma cell lines (A549). It has beenshown to suppress angiogenesis, inflammation, and carcinogenesis. The mechanisms of these activities, however, are unknown. Because ofthese effects, to improve the efficacy of gossypin we made an attempt in the protein binding ofgossypin in this study. In-vitro protein binding of gossypin in purified bovine serum albumin was investigated by equilibrium dialysis. The drugwas highly protein bound; approximately 99.2% and the extent of protein binding remained constant at gossypin concentration in the range of 1-5?g/ml. The extent of binding tends todecrease at lower albumin and higher drug concentrations. Scatchard plot indicates the presence of two binding sites.