Reperfusion injury, a well-known problem in organ transplantation, results from multiple pathologic mechanisms, including platelet/mast cell activation and peroxidation of cell membrane lipids. Relaxin was originally described as an insulin-like hormone produced in the ovaries during pregnancy. It causes vessel dilation and inhibition of platelet and mast cell activation. The present study investigated the protective effect of relaxin against reperfusion injury in liver tissue. We used a model of isolated perfused rat liver to simulate liver transplantation. Organ preservation was performed identical to human transplantation in 20 male Wistar rats. During preservation we applied 64 ng/mL relaxin. In contrast controls (n = 10) had no relaxin treatment. To quantify cell damage, we measured malonyldialdehyde (MDA; end product of lipid peroxidation) and myeloperoxidase activity (MPO; marker for accumulation of neutrophil granulocytes) in the perfusates. The livers were examined immunohistochemically for the same parameters. Relaxin as an additional substance in preservation solutions decreased perfusate MPO and MDA levels by up to 30%, as shown by immunohistochemistry. Our preliminary data suggested that relaxin is a promising agent to reduce hepatocyte damage caused by ischemia-reperfusion injury. Quantitative analysis of MDA and MPO levels in the perfusate is the subject of an ongoing study.