Sex and gender in biomedicine are innovative research concepts of theoretical and clinical medicine that enable a better understanding of health and disease, evidence-based knowledge, effective therapies, and better health outcomes for women and men. Gender medicine, which focuses on the impact of gender on human physiology, pathophysiology, and clinical features of diseases, stimulates new ways of doing research by considering sex and gender at all levels of investigation, from basic research into gene polymorphisms to health behavior. New research questions have been put forward that focus not on differences per se but on the developmnetal path of these differences. In this book, contributions from the fields of neuroscience, addiction research, and organ transplantation exemplify concepts, approaches, methods and results in the field of gender medicine.