Abstract： Objective To analyze the dynamic changes of dendritic ceils (DCs) and their subsets plasmacytoid DC (pDC) and myeliod DC (mDC) in peripheral blood of renal transplantation patients,and to confer the relationship between DCs subsets and graft rejection.Methods White blood cells (WBC) and mononuclear cells (PBMNCs) in peripheral blood of 28 renal transplantation recipients (test group) were measured before operation and at 1st,7th,28th day after operation.The number of DCs and subsets,and pDC/mDC were detected by using flow cytometry,and IL-10 and IL-12 levels were determined by using ELISA before and after operation.Ten volunteers (control group) served as controls.Results The levels of DCs,pDC and mDC before operation in test group were lower than in control group (P＜0.05),but there was no statistically significant difference in pDC/mDC ratio between two groups (P＞0.05).The number of DCs in test group was significantly decreased on the first day after operation up to the lowest level,then slowly increased,and recovered 73.7 ％ at 28th day after operation.The number of mDC and pDC was also decreased after operation,but mDC recovered faster than pDC (P＜0.05).On the day 7th after operation,the number of mDC in the recipients with graft rejection was higher than in those without graft rejection in test group (P＜0.01 ).There was no significant difference before and after operation in the levels of IL-10 and IL-12 in test group.Conclusion The number of DCs and subsets are related to the recipients' immune state,and their abnormality displays unstable immune state of recipients.The number of DCs and subsets can be used as an assistance index to diagnose graft rejection.