Abstract: 
Certain medicinal plants are believed to promote positive health and maintain organic resistance against infection by re-establishing body equilibrium and conditioning the body tissues. It is tempting to speculate that the restorative and rejuvenating power of these herbal remedies might be due to their action on the immune system and some of the medicinal plants are believed to enhance the natural resistance of the body to infections. Plant derived materials (proteins, lections, polysaccharides, etc.) have been shown to stimulate the immune system. Ayurveda and other Indian literature mention the use of plants in treatment of various human ailments. Some of the plants with established immunomodulatory activity are Viscum album, Panax ginseng, Asparagus racemosus, Azadirachta indica, Tinospora cordifolia, Polygala senega, Ocimum santum, Withania somnifera among others. There are a number of plants that have been reported to have immunomodulatory activity. The present paper review plants which have shown experimental and clinical immunomodulatory activity.

Keywords: Immunomodulatory Activity, Sheep Red Blood Cells (SRBC), Cyclophosphamide, Pyrogallol, Heamagglutination Antibody (HA) Titer, Delayed Type Hypersensitivity (DTH), Neutrophil Adhesion Test, Carbon Clearance.