AIM To investigate the rates of pretransplantation fetalmaternal microchimerism(MC) and its effect on rejection in children receiving maternal liver grafts. METHODS DNA or blood samples before liver transplantation(LT) were available in 45 pediatric patients and their mothers. The presence of pretransplantation MC to non-inherited maternal antigens(NIMAs)(NIMA-MC) in the peripheral blood was tested using nested PCRsingle-strand conformation polymorphism analysis for the human leukocyte antigen(HLA)-DRB1 alleles. NIMA-MC was successfully evaluated in 26 of the 45 children. Among these 45 pediatric LT recipients,23 children(51.1%) received transplants from maternal donors and the other 22 from non-maternal donors.RESULTS Among these 26 children,pretransplantation NIMAMC was detected in 23.1%(n = 6),6.1(range,0.8-14) years after birth. Among the children with a maternal donor,the rate of biopsy-proven cellular rejection(BPCR) was 0% in patients with NIMA-MC positivity(0/3) and those with HLA-DR identity with the mother(0/4),but it was 50% in those with NIMA-MC negativity(5/10). Patients with NIMA-MC positivity or HLA-DR identity with the mother showed significantly lower BPCR rate compared with NIMA-MC-negative patients(0% vs 50%,P = 0.04). NIMA-MC-positive patients tended to show lower BPCR rate compared with NIMAMC-negative patients(P = 0.23). CONCLUSION The presence of pretransplantation NIMA-MC or HLADR identity with the mother could be associated with BPCR-free survival in pediatric recipients of LT from maternal donors. AIM To investigate the rates of pretransplantation fetalmaternal microchimerism (MC) and its effect on rejection in children receiving maternal liver grafts. METHODS DNA or blood samples before liver transplantation (LT) were available in 45 pediatric patients and their mothers. The presence of pretransplantation MC to non-inherited maternal antigens (NIMA-MC) in the peripheral blood was tested using nested PCR single-strand conformation polymorphism analysis for the human leukocyte antigen (HLA) -DRB1 alleles. NIMA-MC was successfully evaluated in 26 of the Among the 45 children. Among these 45 pediatric LT recipients, 23 children (51.1%) received transplants from maternal donors and the other 22 from non-maternal donors .RESULTS These 26 children, pretransplantation NIMAMC was detected in 23.1% (n = 6), Among the children with a maternal donor, the rate of biopsy-proven cellular rejection (BPCR) was 0% in patients with NIMA-MC positivity (0/3) and those with HLA-DR identity with the mother (0/4), but it was 50% in those with NIMA-MC negativity (5/10). Patients with NIMA-MC positivity or HLA-DR identity with the mother showing significantly lower BPCR rate NIMA-MC-positive patients tended to show lower BPCR rate compared with NIMAMC-negative patients (P = 0.23). CONCLUSION The presence of pretransplantation NIMA (0% vs 50%, P = -MC or HLADR identity with the mother could be associated with BPCR-free survival in pediatric recipients of LT from maternal donors.