A tremendous increase in the knowledge of herbal drug constituents, their effects, and side effects has occurred in recent years. As a result, many herbal products are undergoing a transition from classic herbal to standardized extracts. Alteration in the immune system can be achieved by immonomodulatory agents. Herbal medicines constitute a major component in all traditional and alternate systems of medicines like Siddha, Ayurveda, Homeopathy, Naturopathy, Traditional Chinese Medicine, and native American Medicine.Many medicinal plants are the rich source of substances which are claimed to induce paraimmunity, the non specific immunomodulation of granulocytes, macrophages, natural killer cells, complement and lymphocytes, and also to the production of various effector molecules generated by activated cells.Evaluation of traditionally used medicines, keeping into account the traditional principles that are applied in drug therapy, may provide leads towards effective drug discovery. This work is an attempt to bridge the gap between ancient historical and the recent scientific evaluation of phytomedicines.