Two extracts E1and E2 were prepared from the dried root of the plant Caesalpinia digyna by extracting with solvents of different polarity. The extracts were standardized with respect to a polyphenol, bergenin, by LC- MS analysis and they were subjected to free radical scavenging activity and in vitro radioprotection studies. Free radical reactions were carried out with superoxide, hydroxyl, and peroxyl radicals and DPPH. In vitro radioprotecting activity was studied by following their effect on gamma-radiation induced lipid peroxidation, protein carbonylation and DNA damage. The results indicated that E1 with higher free radical scavenging ability is also a more potent inhibitor of radiation induced damage to proteins, DNA and liposomes than E2. Comparing the results with those for bergenin indicated that bergenin alone is not responsible for the free radical scavenging ability and in vitro radioprotection. The studies also confirmed that the extracts enriched with bergenin are more effective than the isolated polyphenol, bergenin.