Nagbala is mentioned as single drug Rasayana in Brihattrayee and used in the management of various diseases. Grewia hirsuta Vahl., is one of the species considered as Nagbala by different scholars. So it was selected as Nagbala to evaluate its immunomodulatory activity. Aim – Evaluation of immunomodulatory activity of Nagbala (Grewia hirsuta Vahl) root decoction and powder by DTH method in swiss albino mice. Methodology – Collection, identification and authentification of drug was done. Immunomodulatory activity was performed on Swiss Albino Mice by DTH model, using Churna and Kwath of Nagbala (Grewia hirsuta Vahl) root orally. Result – Results of screening of immunomodulatory activity showed significant improvement in paw volume, in treatment group. The oral administration of the drug was also found significant increase in WBC count.