Objective To study the effect and possible mechanism of Panax ginseng fructus juice concentrate on immune injury induced by cyclophosphamide in mice.Methods Seventy-two specific pathogen-free （SPF） C57BL/6J male mice were randomly divided into six groups （12 per group）， including blank group， cyclophosphamide group， positive drug group， low-， middle- and high-dose Panax ginseng fructus juice concentrate groups （83， 166， 249 mg/kg）. From day 1 to day 14， mice in three groups of Panax ginseng fructus juice concentrate were intragastrically administrated with concentrate at volumes of corresponding dosage， and mice in blank group and cyclophosphamide group were gavaged with the same amount of distilled water. Mice in positive drug group were also intragastrically administrated with the same amount of water from day 1 to day 7， and then from day 8 to day 14， gavaged with 20 mg/kg levamisole hydrochloride （LH）. From day 12 to day 14， mice in cyclophosphamide group， positive drug group and three Panax ginseng fructus juice concentrate groups were intraperitoneally injected with 80 mg/kg cyclophosphamide， while those in blank group were injected with the same amount of normal saline. At the end of the experiment， the spleen index was calculated， leukocyte （WBC）， lymphocyte （LYM） and LYM% in peripheral blood were measured， and the activities of lactate dehydrogenase （LDH） and acid phosphatase （ACP） in serum and spleen， activities of superoxide dismutase （SOD）， catalase （CAT） and malondialdehyde （MDA） content in spleen homogenate were measured.Results There was no significant difference in body weight among groups （P>0.05）. Compared with blank group， the spleen index of mice decreased （P<0.01）， WBC， LYM and LYM% decreased， the activity of ACP in serum and spleen of mice decreased or showed a downward trend， the activity of SOD and CAT in spleen decreased and the content of MDA increased in cyclophosphamide group（P<0.05）. Compared with cyclophosphamide group， spleen index of mice in the panax ginseng fructus juice concentrate groups increased （P<0.05， P<0.01）， LYM% in the low- and high-dose panax ginseng fruit juice concentrate groups increased， activity of ACP increased or showed an upward trend in the panax ginseng fructus juice concentrate groups， activities of SOD and CAT showed an increasing trend in the low-dose group of panax ginseng fructus juice concentrate， and contents of MDA decreased in all three groups of panax ginseng fructus juice concentrate （P<0.05， P<0.01）.Conclusion To some extent， panax ginseng fructus juice concentrate can improve the immune injury induced by cyclophosphamide in mice， which may be related to its effect of reducing oxidative damage of the immune organs in mice.