摘要：Background: In the past few decades, the incidence of cardiometabolic diseases and disorders of the liver, kidney, pancreas, heart, and lung, have been increasing in Western and Asian countries, including Japan. Numerous factors, including abnormal body weight (obesity, overweight, or underweight), infrequent exercise, and other unfavorable lifestyle factors (e.g., smoking and heavy alcohol drinking) have been proposed as risk factors for the development and the progression of diseases, such as type 2 diabetes, hypertension, and dyslipidemia, which ultimately lead to impaired organ function and possibly death. However, the mechanisms that link these risk factors with diseases are still poorly understood, and the potential treatments, including pharmacotherapy and diet, have not been fully evaluated. Methods: In 2011, we established a new collaborative research program, the Saitama Cardiometabolic Disease and Organ Impairment Study (SCDOIS). This multidisciplinary observational epidemiological research study was designed to cover several high-profile diseases and some traditional fields of internal medicine, as well as apparently unrelated fields and particular lifestyle factors, such as unhealthy eating behaviors. In a series of studies, apparently healthy subjects who underwent a regular medical checkup were retrospectively identified based on the results of their medical checkups. In this way, the incidence, prevalence, causality, and clinical relevance of specific conditions and diseases have been investigated in cross-sectional analyses of 100,000 - 200,000 adults, and in longitudinal studies of several thousand subjects who underwent medical checkups multiple times. Discussion: This article describes the background, rationale, purpose, and methods of the SCDOIS. Using data obtained from annual medical checkups, our goals are to 1) establish criteria or identify clinical features that would enable clinicians to detect the presence of abnormal conditions associat