Objective:To explore the immunomodulatory properties of 80% ethanol extract and butanol fraction of Gentiana olivieri(G. olivieri) Griseb on Balb/C mice.Methods:The study was performed with basic models of immunomodulation such as the humoral antibody response(hemoglutination antibody titres), cell mediated immune response(delayed type hypersensitivity and in vivocarbon clearance or phagocytosis). Ethanol(80%) extract of flowering aerial parts of G.olivieriand its butanol fraction were administered p.o.(orally) to the mice. Levamisole, 2.5 mg/kg was used as standard drug.Results:There was a potentiation of immune response to sheep red blood cells by cellular and humoral mediated mechanisms comparable to levamisole(2.5 mg/kg) by both 80% ethanol extract and the butanol fraction at doses of 50-200 mg/kg in male Balb/C mice. Both significantly(P<0.01) potentiated the humoral immune response in cyclophosphamide(250 mg/kg)immunosupressed mice at 100 and 200 mg/kg of each extract and fraction as compared to control.The potentiation of delayed type hypersensitivity response was statistically significant(P<0.01) at200 mg/kg of ethanol extract and 100, 200 mg/kg of butanol fraction as compared to control. The phagocytosis was significant at 200 mg/kg with butanol fraction ofG. olivieri.Conclusions:The results reveal the immunostimulant effects of plantG. olivieriin mice by acting through cellular and humoral immunity in experimental models of immunity in mice. Butanol fraction is the most effective at a dose level of 200 mg/kg. Objective: To explore the immunomodulatory properties of 80% ethanol extract and butanol fraction of Gentiana olivieri (G. olivieri) Griseb on Balb / C mice. Methods: The study was performed with basic models of immunomodulation such as the humoral antibody response (hemoglutination antibody titres), cell mediated immune response (delayed type hypersensitivity and in vivocarbon clearance or phagocytosis). Ethanol (80%) extract of flowering aerial parts of G. olivieri and its butanol fraction were administered po (orally) to the mice. Levamisole, 2.5 mg / kg was used as standard drug. Results: There was a potential of immune response to sheep red blood cells by cellular and humoral mediated mechanisms comparable to levamisole (2.5 mg / kg) by both 80% ethanol extract and the butanol fraction at doses of 50-200 mg / kg in male Balb / C mice. Both significantly (P <0.01) potentiated the humoral immune response in cyclophosphamide (250 mg / kg) immunosupressed mice at 100 and 200 mg / kg of each extract and fractio n as compared to control. The potentiation of delayed type hypersensitivity response was significantly (P <0.01) at200 mg / kg of ethanol extract and 100, 200 mg / kg of butanol fraction as compared to control. The phagocytosis was significant at 200 mg / kg with butanol fraction of G. olivieri. Confc: The results reveal the immunostimulant effects of plant G. olivieriin mice by acting through cellular and humoral immunity in experimental models of immunity in mice. Butanol fraction is the most effective at a dose level of 200 mg / kg.