Objective: To evaluate uric acid renal excretion, hyperuricemia, renal dysfunction, and prognosis in patients with decompensated severe heart failure, as there are few data available. Methods: One hundred and twenty-two patients, hospitalized for heart failure decompensation, in NYHA class IV, were classified into 3 groups as follows. Pilot group [ejection fraction (EF)V0.45, n=16], group 1 (EFV0.45, n=90), and group 2 (EFN0.45 and valvular dysfunction, n=16). The patients in groups 1 and 2 underwent assessment of creatinine and uric acid clearance before and after pyrazinamide, to estimate uric acid tubular secretion. Uric acid clearance b6.8 mL/min and secretion b170 Ag/min were considered reduced. In groups 1 and pilot (n=106), mortality was analyzed by Cox regression model, and the prognostic value of hyperuricemia was assessed by ROC curve. Results: In groups 1 and 2, respectively, serum uric acid was 511.7 and 422.5 Amol/L, and creatinine clearance was 46.7 and 61.4 mL/min. Uric acid clearance (3.2 vs. 3.9 mL/min) and tubular secretion (116 vs. 128 Ag/min) were not different, but lower than normal values. In groups 1 and pilot, the 12-month mortality was 46.4% (CI 95%: 36.7%-56.0%). At end of follow-up, mortality was associated with impaired creatinine clearance ( pb0.001), but not with hyperuricemia ( p=0.236). Conclusions: In patients with decompensated severe heart failure, the tubular secretion and the clearance of uric acid were reduced. Renal dysfunction was associated with mortality, but hyperuricemia was not.