Objective To explore the roles of B lymphocyte and plasma cell in liver allograft re-jection to find the evidences of humoral factor participating in the rejection. Methods Immunohisto-chemical inspection of C4d, CD20+ B lymphocytes and CD138+ plasma cells were performed in 34 liver biopsy specimens from 25 patients with hepatic injury and their preoperative specimens. Then we ob-served the variances of the above parameters in the liver biopsy specimens and the differences of them with different hepatic injuries. We further observed the relation of the presence of CD20+ B lympho-cytes and CD138+ plasma cells to C4d positivity. Meanwhile, we compared the difficulties of clinical therapy with different presences of CD20+ B lymphocytes and CD138+ plasma cells in the liver biopsy specimens. Results The positive ratios of CD20+B lymphocytes and CD138+ plasma cells were signif-icantly higher in the acute rejection group than in the non-rejection group(P<0. 05 and P<0. 01).The positive ratios of CD20+ B lymphocytes were markedly higher in the chronic rejection group than in the non-rejection group(P<0. 05). There was no difference in CD138+ plasma cells between the 2 groups. The degrees of hepatic injury could not influence the positive ratioes of CD138+ plasma, but the positive ratioes of CD20+ B lymphocytes in the heavy hepatic injury groups was higher than in the slight hepatic injury groups(P<0. 05). CD20+ B lymphocytes and CD138+ plasma cells presented fol-lowing C4d(P<0. 01 and P<0. 05). The effective power of steroid in the all-positive group was obvi-ously lower than in the all-negative group(P<0. 05). Conclusion Humoral immune may participate in some liver allograft rejection. It would be more favorable for observing and prewarning the humoral re-jection by finding CD20, CD138 and C4d by immunohistochemical staining in liver biopsy specimens with hepatic injury after liver transplantation. It would be helpful for choosing the therapeutic regi-mens of liver allograft rejection. Key words: Liver transplantation; Rejection; C4d; B lymphocytes; Plasma cell