Metabolic syndrome is one of the most important risk factors of atherosclerotic disease, and visceral obesity is regarded as a principle component of metabolic syndrome. Medical checkups for metabolic syndrome were started in 2008 for the purpose of promoting lifestyle modification through health guidance. The original diagnosis of metabolic syndrome in Japan was presented by the Examination Committee of Criteria for Metabolic Syndrome in April 2005. This guideline defines the waist circumference measurement as an essential component, accompanied by at least two of the following three risk factors: dyslipidemia, a raised blood pressure, and glucose intolerance, and these risk factors were based on multiple representative Japanese cohort studies. However, there are some problems with these standards. For example, it is often the case that accurate evaluation is difficult because variable factors such as meals influence the serum triglyceride level. This influences the reliability of the results of cohort studies. In this symposium, problems with this guideline were presented along with an introduction to the cohort study on which the concept of the syndrome was based. I compiled a cohort study related to metabolic syndrome, and pointed out some problems from the viewpoint of clinical laboratory medicine.