A large number of pharmacological agents affect the serum concentration of uric acid. Some drugs raise serum uric acid level by an increase in uric acid production or a decrease in uric acid excretion, while others lower serum uric acid level by a decrease in uric acid production or an increase in uric acid excretion. In addition, some drugs show so-called biphasic effect; ie, hyperuricemic in lower doses but hypouricemic in higher doses. Hyperuricemic agents contribute to gout and/or urate nephropathy. Among them, pyrazinamide is often used to determine the defective site(s) of uric acid transport in renal tubules in conjunction with uricosuric agents, such as benzbromarone or probenecid. In contrast, the clinical significance of hypouricemic agents other than uricosuric agents has not been emphasized. However, some may induce acute uric acid nephropathy by a significant increase in uric acid excretion. In this review, drugs affecting uric acid metabolism are summarized with regard to their mechanism of action and clinical significance.