The present invention is about the novel synergistic herbal formulation useful in improving the immunity level. Herbal formulation comprises plant preparation or active component of plant extract together with conventional additives to form the oral dosage forms, viz. tablets. Formulation comprises of Glycyrrhiza glabra, Nelumbo nucifera, Prunella vulgaris and Zizyphus jujuba. The present investigation reveals that the herbal formulation is a potent immunostimulant, stimulating both the specific and non-specific immune mechanisms. So, it may be used in viral infections also.