This short paper for one of the world's leading bioethics journals introduces readers to medical tourism - the travel of patients from their home country to another for the primary purpose of seeking medical treatment. The paper divides medical tourism into three types: (1) Medical tourism for services illegal in both the patient's home and destination countries (e.g., organ transplant tourism); (2) Medical tourism for services that are illegal in the patient's home country but legal in the destination country (e.g., some forms of fertility tourism, euthanasia tourism, experimental drug tourism); (3) Medical tourism for services legal in both the home and destination country (e.g., traveling abroad for a heart valve or hip replacement). The paper then discusses several difficult ethical and regulatory challenges posed by each type of medical tourism.