Gymnemic acid is a mixture of triterpenoid saponins of oleanane class, isolated from Gymnema sylvestre Wild R.Br (family: Asclepidaceae), an herbal plant used in traditional medicine to treat diabetes. Effect of gymnemic acid (0.1–20 μg/mL) on in vitro mitogen (concanavalin A and lipopolysaccharide)-induced splenic lymphocyte proliferation was studied using rat as model. Significant (p < 0.05) stimulation of lymphoproliferation was observed in cultures treated with 10 and 20 μg/mL concentration of gymnemic acid in the absence or presence of mitogens. The present study suggests that gymnemic acid has immunomodulatory property, stimulating lymphoid components of immune system, and the traditional knowledge of anti-diabetic property of G. sylvestre is scientifically supplemented with its immunomodulatory properties. Copyright © 2015 John Wiley & Sons, Ltd.