This review explores the relationship between uric acid or urate and the pathogenesis of renal impairment. The following points and conclusions are emphasized: (1) uric acid is an end product of purine degradation in humans and normally depends upon renal excretion for the majority of its elimination from the body; (2) massive urate overproduction - usually occurring acutely because of tumor lysis, rhabdomyolysis, or some other cause of rapid nucleic acid turnover or tissue destruction - tends to cause acute renal failure because of an increase of intratubular uric acid precipitation and obstruction; (3) chronic urate overproduction (with increased urate excretion) is more likely to be associated with stones or gout than with acute renal failure; (4) chronic asymptomatic hyperuricemia is unlikely to cause renal disease, gout, or stones, but is associated with cardiovascular impairment over the long term, and (5) asymptomatic hyperuricemia may serve as an indicator of renal vascular disease, or, to the extent that it may reflect insulin-induced acceleration of renal tubule urate reabsorption, hyperuricemia may serve as an indicator of insulin resistance. Therefore chronic asymptomatic hyperuricemia may predict the adverse cardiovascular consequences of insulin resistance.