Allogeneic hematopoietic stem cell transplantation and solid organ transplantation have become established treatments offered to patients for whom there are otherwise no curative treatment options. Unfortunately, these therapeutic modalities are associated with severe complications that limit its applicability. Alloimmunity is an important cause of morbidity and mortality after both organ transplantation and allogeneic hematopoietic stem cell transplantation and represents a major barrier to the more wide-spread use of these treatment modalities. Statins are a class of lipid-lowering drugs, which also posses immunomodulatory effects. Results from preclinial research and early-stage clinical studies indicate that treatment with statins could be beneficial for the prevention and treatment of graft-versus-host disease and transplant rejection. In addition to preventing graft-versus-host disease or graft rejection statins possess several other effects that might prove beneficial in the setting of transplantation, such as cardiovascular protection and antineoplastic activity. Here we summarize the current knowledge about the immunomodulatory effects of statins and discuss the clinical implications for their use in patients undergoing stem cell transplantation or solid organ transplantation.