Abstract: The present invention provides a novel pharmaceutical composition consisting of a combination of three coumarinolignoids of formula 1, 2 and 3 isolated from the seeds of the plant Cleome viscosa along with a pharmaceutically acceptable carrier useful as a immunomodulator. The invention also describes the ability of the compounds to modulate humorral and cell mediated immune response. It further provides a process for the preparation of a novel pharmaceutical composition of the said three coumarinolignoids in an optimized ratio to modulate humorral and cell mediated immune response.