Inclusion Criteria: - Histologically proven aggressive B-cell Non-Hodgkin's lymphoma (IWF classification D-H) with: - Bone marrow involvement less than 30% demonstrated by aspiration - Age-adjusted International Prognostic Index (IPI) 0-2 - Measurable or evaluable disease - ECOG performance status 0-2 - Life expectancy greater than or equal to 12 weeks - Absolute neutrophil count greater than 1.5 x 109/L - Platelet count greater than 100 x 109/L - Adequate organ function (serum creatinine less than or equal to 2.0 mg/dL, SGOT/AST and SGPT/ALT less than 3 x the upper limit of normal, hemoglobin greater than or equal to 10g/dL and total serum bilirubin less than or equal to 1.5 mg/dL) - Left Ventricular Ejection Fraction (LVEF) greater than or equal to 50% at rest by MUGA or echocardiogram - Previously untreated with chemotherapy or radiotherapy - Before any study specific procedure or before study medication was administered, the subject was to give written informed consent for participation in the study Exclusion Criteria: - Burkitt's or B-lymphoblastic lymphoma - CNS involvement - Active infection requiring treatment with systemic (intravenous or oral) anti-infectives (antibiotic, antifungal, antiviral) within 72 hours of chemotherapy - Use of anti-hypertensives within 12 hours of start of chemotherapy - Known HIV infection - Any premalignant myeloid condition or any malignancy with myeloid characteristics (e.g., myelodysplastic syndromes, acute or chronic myelogenous leukaemia) - Prior malignancy within the last 5 years, with the exception of surgically cured basal cell carcinoma, squamous skin cell carcinoma, or in situ carcinoma of the cervix - Prior bone marrow or stem cell transplantation - History of impaired cardiac status, e.g. severe heart disease,cardiomyopathy, or congestive heart failure - Major surgery within 2 weeks prior to randomization - Subject is evidently pregnant (e.g., positive HCG test unless termination is proven) or is breast feeding - Subject is not using adequate contraceptive precautions - Known hypersensitivity to E coli-derived products (e.g., Filgrastim,HUMULIN® Insulin, L-Asparaginase, HUMATROPE® Growth Hormone, INTRON A®) - Any psychiatric, addictive or other kind of disorder which compromised the ability of the subject to give written informed consent and/or to comply with study protocol procedures - Prior exposure to pegfilgrastim - Subject is currently enrolled in, or has not yet completed at least 30 days since ending other investigational device or drug trial(s) or is receiving other investigational agent(s) - Subject has previously entered this study