The present invention relates to synergistic compositions for the treatment of one or more associated conditions of arthritis or rheumatoid arthritis osteoarthritis. More particularly, novel synergistic compositions which comprises a combination of therapeutically effective amounts of: a) an alcoholic/hydroalcoholic extract of Tamarindus indica seed comprising proanthocyanidins either alone or in combination with water extract of Tamarindus indica seed comprising polysaccharides, b) a Curcuma longa rhizome extract comprising curcuminoids, c) optionally containing pharmaceutically or nutraceutically or dietetically acceptable carriers/excipients. The invention also relates to a method of treating one or more associated conditions of arthritis or rheumatoid arthritis or osteoarthritis using synergistic composition.