The longitudinal behavior of serum uric acid was studied by regular determinations made on a total of 195 subjects (of whom 53 were males and 142, females) between 1968 and 1978. The concentration of uric acid showed a significant increase within ten years irrespective of age, sex, and body weight. Nutritional influences, problems of physical and mental activity, therapeutical measures and agents, as well as hormonal alteration are discussed as possible cause thereof. There were no correlation between change in relative weight and uric acid level. Serum cholesterol and uric acid trends showed negative correlations in young men and positive correlations in older men.