Background We investigated the role of 1, 25-dihydroxyvitamin D3 (1, 25-(OH)2D3) in preventing allograft from acute rejection following orthotopic liver transplantation. Methods A rat orthotopic liver transplantation model was used in this study. SD-Wistar rats served as a high responder strain combination. Recipients were subjected to administration of 1, 25-(OH)2 D3 at dosages ranging from 0.25 μg·kg-1*d-1 to 2.5 μg·kg-1*d-1. Survival after transplantation as well as pathological rejection grades and IFN-γ mRNA, IL-10 mRNA transcription intragraft on day 7, and day 30 post-transplantation were observed. rnResults After recipients were treated with 1, 25(OH)2 D3 at dosages of 0.5 μg*kg-1*d-1 or 1.0 μ g*kg-1*d-1, survivals of recipients were prolonged. Ninety-five percent confidence intervals of survival were 46-87 days and 69-102 days (both P=0.0005 vs control group), respectively. On day seven post-transplantation, relative levels of IFN-γ mRNA transcription were 0.59±0.12 and 0.49±0.16, which was higher than the control group (P=0.005, P=0.003, respectively). Relative levels of IL-10 mRNA transcription were 0.83±0.09 and 0.76±0.09, which was lower than the control group (P=0.002, P=0.003, respectively). At a dosage of 0.5 μg·kg-1*d-1, the median of pathological rejection grade on day seven and on day thirty post-transplantation were 1.5 and 2.0 in comparison with the CsA-treated group (P=0.178, P=0.171, respectively). At a dosage of 0.5 μg·kg-1*d-1, the median of pathological rejection grade on day seven and day thirty post-transplantation were 1.5 and 1.5 in comparison with CsA-treated group (P=0.350, P=0.693, respectively).Conclusion After each recipient was treated with 1,25-(OH)2 D3 at a dosage of (0.5-1.0) μg·kg-1*d-1, transcription of cytokine intragraft was accommodated effectively and deviated to Th2 type, resulting in alleviation of acute rejection. 1, 25-(OH)2 D3 can prolong survival of recipient after orthotopic liver transplantation.rn