Objective: Aqueous extract of Tricosanthes dioica Roxb.were administered oraly at doses of 100, 200 mg/kg/day for 45 days in wistar albino rats. Immunomodulatory effect and biochemical and haematological changes were tested by standard methods. Results: Aqueous extract of theTricosanthes dioica It enhances the production of RBC, WBC and hemoglobin. It does not affect the biochemical parameters. Conclusion: An oral administration of the aqueous extract of Tricosanthes dioica Roxb. showed immunomodulatory effect in rat. Roxb. showed increasing antibody production in dose dependent manner.