Rasburicase was administered at a fixed dose of 3 mg to treat 287 episodes of elevated serum uric acid levels (>7 mg/dL) in 247 adult patients with hematological malignancies. The median total dose of 36 μg/kg (range: 18-65) was a fraction of the recommended total pediatric dose of 0.75-1.0 mg/kg. The median change in uric acid levels at 24 h was -4.1 mg/dL (range: -12 to +1) and -45% (range: -95 to +9). Uric acid levels normalized at 24 h in 72% of patients. There was no relationship between the weight-based dose and uric acid decline. The only predictor of success was the baseline uric acid; the failure rate was 84% with baseline level >12 mg/dL and 18% if it was ≤ 12. Uric acid levels continued to decline beyond 24 h in most patients without additional treatment. Serum creatinine remained stable over 24 h, and declined over 48 h and 7 days. There was no relationship between the extent of reduction in uric acid levels and serum creatinine. We conclude that a single 3-mg dose of rasburicase, used with close monitoring, is sufficient to treat most adults with uric acid levels up to 12 mg/dL.