The use of plants for the treatment of various diseases was recorded in the history. Many conventional medicines originate from plant sources: many decades ago, most of the few effective drugs were plant-based. Examples include quinine (from cinchona bark), digoxin (from foxglove), morphine (from the opium poppy) and aspirin (from willow bark). The discovery and development of new drugs from plant sources continues, with drug companies engaged in large-scale pharmacologic screening of herbs. Arthritis is a condition typically characterized by pain, aching, stiffness and swelling in and around one or more joints. Rheumatoid arthritis (RA) is a disorder in which the body's own immune system starts to attack body tissues. Ricinus communis, the castorbean or castor-oil-plant is a species of flowering plant in the spurge family, Euphorbiaceae. Many authors have reported that the plant has promised Antioxidant activity, Antinociceptive activity, Antiulcer activity, Antiasthmatic activity, Anti-fertility activity, Antihistaminic Activity etc cited in literature review. The present study is aimed to evaluate the methanolic leaf extract of Ricinus communis for acclaimed anti-arthritic activity by using protein denaturation method. Diclofenac sodium is used as a standard drug. From the results of the present study it can be stated that the methanolic leaf extract of Ricinus communis at two different concentrations (250mcg/ml & 500mcg/ml) is capable of inhibiting the denaturation of protein in rheumatic disease.