There are a number of human diseases, which can lead to organ failure. The consequence is often the need for a transplant. The number of performed operations is very low due to the shortage of organs for transplantation. As a consequence, the number of people waiting for transplant is still growing. The solution to this situation may be xenotransplantation. Xenotransplantation word comes from the Greek xenos meaning stranger, the other. It is defined as any procedure that involves the transplantation, implantation or infusion of tissues or zoonotic organs into a human recipient, but also human body fluids, cells, tissues, organs (or fragments) that have ex vivo contact with zoonotic cells, tissues or organs. One of the obstacles of the xenograft transplantation is the risk of animal pathogens transmission to the humans. Viruses that pose risk in the non-human primates-to-human xenotransplantation includes: the human immunodeficiency virus - HIV and the Marburg virus described in this paper. In addition viruses, which is a problem in pig-to-human xenotransplantation have also been described, including: porcine endogenous retrovirus - PERV, porcine cytomegalovirus - PCMV, porcine lymphotropic herpesvirus - PLHV and hepatitis E virus - E - HEV. This review of literature is the latest knowledge of the microbiological safety of xenotransplantation.