Although hyperuricemia is a well-known adverse effect of cyclosporine (CsA) treatment, there are contradictory data regarding the effect of tacrolimus on uric acid levels. The aim of this study was to examine the influences of CsA and tacrolimus-based treatment regimens on serum uric acid levels in 155 renal transplant recipients with normal allograft function who underwent renal transplantation between 1999 and 2002. Serum uric acid levels were recorded at 1, 6, 12, 18, and 24 months follow-up. The patients were treated with CsA-based (n = 73), tacrolimus-based (n = 47), or conversion from CsA-based to tacrolimus-based (n = 35) immunosuppressive regimens. Serum uric acid levels for patients in the CsA and tacrolimus groups were 6.3 +/- 1.6 versus 7.9 +/- 1.9 mg/dL and 6.5 +/- 1.8 versus 8.0 +/- 1.8 mg/dL at the study outset and 24 months, respectively. Both of the treatment regimens showed progressively increasing serum uric acid levels (P < .001). Serum uric acid levels of patients with treatment conversion from CsA to tacrolimus were 8.6 +/- 2.8 mg/dL before conversion and 8.1 +/- 1.9 mg/dL after conversion. There was no alteration in serum uric acid levels after the change of treatment (P > .05). These findings indicate that, compared with CsA, tacrolimus offers no advantage for serum uric acid levels in renal transplant recipients.