This study is a prospective, open-label, multicentre study. Hundred eligible patients with stage III or IV non-Hodgkin lymphoma (NHL) or acute lymphoblastic leukemia (ALL) with a peripheral white blood cell (WBC) count of > 25,000/µL or any leukemia or lymphoma with plasma uric acid level of at least 8 mg/dL will be treated with rasburicase 0.20 mg/kg body weight intravenously for 4 days. The primary endpoints viz., the percentage of reduction in plasma uric acid at 4 hrs after uric acid-lowering therapy, plasma uric acid AUC 0-96 hr and incidence of adverse events will be assessed during 11 days study period.