It has been reported that the prevalence of hyperuricemia in Japan is 20-25% in adult male population and has been increasing at least until a few years ago. Although epidemiological data for the prevalence of gout in Japan is limited, a recent study conducted in a local area of Wakayama prefecture reported a prevalence of 1.1% in men. Japanese national census data revealed that the number of individuals visiting hospitals with a self-diagnosis of gout has been increasing. The census data also showed that the proportion of individuals with obesity(BMI > or = 25) has been increasing in male population, probably due to decreasing physical exercise. This epidemic of obesity may be one cause for a recent increase in hyperuricemic individuals in Japan.