Japan was defeated in World War II and almost all of the nation was demoralized by the destruction and damage to much of the nation. The medical and health care system during and before World War II needed to be reformed radically and fundamentally since almost all medical and health institutes were destroyed. On the other hand, many health personnel came back from overseas after the war. Japanese modern medicine had developed on the basis of German medicine; however, many aspects of American medicine, including public health and democracy, were rapidly introduced following the end of World War II. The American type of health center was established and many laws concerning medical and health care were enacted in 1947-1948. One of them was "The Health Center Law." The National Health Insurance Act was enacted in 1958 and the total population has been covered by health insurance plans since 1961. Many physicians quit the health centers and they have worked as clinicians under the National Health Insurance scheme, because health centers were introduced before adequate education and research existed in the field of public health. On the other hand, the health insurance scheme was in its golden age during the high economic growth period of the 1960s. Japan has succeeded in all forms of modern technology and economy for the past 30 years and is now one of the top nations in the field of medical and health care, such as the numbers of clinics and hospitals and beds, the frequency of consulting with a doctor, length of hospital stay, examinee rates in mass health examinations in the community and workplace and so on. Health conditions have changed drastically from the 1950s to the present. Therefore, health centers do not fit current health needs. For example, mortality from tuberculosis, acute infections diseases and also stomach and uterus cancers and apoplexy have decreased rapidly while mortality from chronic diseases, especially lung, breast and rectal cancers, and myocardial infarction have increased gradually. Changes of life style resulting from rapid economic growth are suspected to be important causes of the change in the prevalence of these diseases. Mass health examination was important and effective as a preventive measure against tuberculosis, especially as a means of early detection and early treatment. However, it is not now effective against chronic diseases. The screening examination has resulted in identifying many patients suspected of being ill. Every examiner must be able to distinguish pathologic findings from physiologic changes of aging. Every patient must, therefore, understand his/her individuality and evaluate the result of his/her efforts to improve life style by receiving a health examination. Accordingly, the aim of health examination has changed from early detection to health support for the examinee. During the decades when life expectancy was less than 50 years of age, it was not necessary for people to plan for retirement. Moreover, there was little burden on younger generations to provide care for the aged people because there were few old people more than 70 years of age and the birth rate was high. Nowadays, elderly people face many years of life after retirement and there are too many aged people in relation to the number of younger persons. As for medical care services, many new medical needs have emerged in recent years, including "quality of life," "palliative medicine in terminal care," "establishment of a primary care system" and "comprehensive care connecting health and medical care with welfare" etc. Improved living standards resulting from economic growth, called the "economic miracle" internationally, have helped to bring about a rapid and wide range of change in daily lifestyle, such as eating habits, working conditions and environment. The Ministry of Health and Welfare has made every effort to revise the laws in relation to health and medical care systems, in order to adjust to recent