With the rising popularity of positive psychology, research on forgiveness has flourished. Forgiveness has been found to have application to the field of medicine. We review definitions and describe potential physical and mental benefits of forgiveness. We (1) address potential mechanisms by which forgiveness might affect physical health, (2) evaluate the research on forgiveness and mental health, (3) summarize research on interventions to promote forgiveness, (4) examine issues specifically related to medicine in which forgiveness might play an important role, and (5) discuss forgiveness of self and others and seeking forgiveness in light of those applications. We emphasize the importance of one's motive in forgiving, noting that altruistic motives hold greater benefits than do self-interested motives.