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Background Liver enriched natural killer (NK) cells are of high immune activity. However, the function of donor liver NK cells in allogeneic liver transplantation (LTx) remains unclear. Methods Ten Gy of whole body gamma-irradiation (WBI) from a 60 Co source at 0.6 Gy/min was used for depleting donor-derived leukocytes, and transfusion of purified liver NK cells isolated from the same type rat as donor (donor type liver NK cells, dtl NKs) through portal vein was performed immediately after grafting the irradiated liver. Post-transplant survival observation on recipients and histopathological detection of liver grafts were adoptive to evaluate the biological impact of donor liver NK cells on recipients' survival in rat LTx. Results Transfusion of dtl NKs did not shorten the survival time among the recipients of spontaneous tolerance model (BN to LEW rat) after rat LTx, but prolonged the liver graft survival among the recipients depleted of donor-derived leukocytes in the acute rejection model (LEW to BN rat). Compared to the recipients in the groups which received the graft depleted of donor-derived leukocytes, better survival and less damage in the allografts were also found among the recipients in the two different strain combinations of liver allograft due to transfusion of dtl NKs. Conclusions Donor liver NK cells alone do not exacerbate liver allograft acute rejection. Conversely, they can alleviate it, and improve the recipients' survival.