Xenotransplantation, in its broadest sense, is the transplantation, implantation, or infusion of cells, tissues, or organs from one species to another. While there is a high demand for human tissues, cells, and organs for use in clinical transplantation, they are often in short supply. Recent scientific and biotechnological advancements, coupled with the scarcity of human allografts, have led to renewed interest in developing exploratory treatment strategies that use xenotransplantation products in human recipients. However, despite its potential benefits, the use of xenotransplantation is still limited due to various considerations, as discussed in this review of the past, present, and future directions of xenotransplantation. One of the key ethical concerns surrounding xenotransplantation is the potential impact on the animals from which the cells, tissues, or organs are obtained. As with genetic modification to fix genetic defects or prevent disease, the ideal outcome for these animals is that they will be better off as a result of the change. However, unless there are major changes in the way science is taught to incorporate ethics into recognized scientific theory and practice, these concerns will not be adequately addressed