Xenotransplantation, i.e. the transplantation of organs (tissues, cells) from animals into humans has been a major question in medicine for many years. Based on the ever increasing shortage of suitable donor organs, the research of xenotransplantation grew more intensive than ever before. The problems associated with xenotransplantation can be divided into four categories: i./ immunological, ii./ physiological, iii./ infectious-microbiological, iv./ ethical. In this study the author attempts to summarize the possibilities of xenotransplantation, the problems associated with it, and their possible solutions.