Previous study of Czech Lymphoma Study Group (4_2002)have shown that intensive induction (MegaCHOP - Cyclophosphamide 3 g/m2, Vincristine 2 mg, Adriamycin 75 mg/m2, Prednisone 300 mg/m2 every three weeks with G-CSF for three cycles, followed by ESHAP - Etoposide 240 mg/m2, Cisplatin 100 mg/m2, Solumedrol 2000 mg and cytarabine 2000 mg/m2 for three cycles every three weeks with G-CSF) followed by intensive consolidation (BEAM) and stem cell support improves progression-free survival in adult patients (18-65 years old) with aggressive B-cell lymphoma (namely, diffuse large B-cell lymphoma, primary mediastinal B-cell lymphoma and follicular lymphoma grade II) with aaIPI 2 and namely, with aaIPI 3. This study was aimed to find out if addition of four to six doses of Rituximab 375 mg/m2 on first day of every cycle of intensive induction further improves prognosis of these patients.