To investigate the effect of non-denatured type-I collagen (NDC-I) on the intestinal barrier of immunocompromised rats,totally 36 male SD rats were randomly divided into four groups,each with nine rats.NDC-I (NDC-I group,10.0 mg/(kg·d)),Spleen amino peptide (positive control group,0.42 mg/(kg·d)) and equal volume of distilled water (control group and model group) were intragastrically administered respectively,and the experiment period was 30 days.On the 24th and 25th days,rats of control group were intraperitoneally injected with distilled water,and the others were intraperitoneally injected with cyclophosphamide (40 mg/(kg·d)) once a day to establish the immunocompromised model.The results showed the level of DAO,ET,and D-lactate in the NDC-I group significantly reduced (P<0.01) compared with the model group.Moreover,sIgA content in the small intestinal mucus significantly increased(P<0.01).Besides,the damage of the jejunum was reduced shown by pathological analysis.According to these results,the NDC-I treatment showed a certain regulatory effect on the intestinal barrier of cyclophosphamide-induced immunocompromised rats.