Inclusion Criteria:

- Age: 18 - 65 years

- Risk group: 1) Progression on primary therapy 2) Initial or subsequent relapse

- Histology: Diagnosis of relapsed aggressive non-Hodgkin lymphoma, whenever possible
confirmed by an excision biopsy of a lymph node or by a sufficiently large biopsy of
an extranodal site if no lymph node lesion is present. The expression of the CD20
antigen must be demonstrated in the primary lesion or in the relapse. Specifically,
the following entities can be treated in this study:

B-NHL:

Grade III B follicular lymphoma Diffuse B-cell lymphoma centroblastic immunoblastic
plasmoblastic anaplastic-large-cell T-cell rich B-cell lymphoma Primary effusion lymphoma
Intravascular B-cell lymphoma Primary mediastinal B-cell lymphoma Mantle cell lymphoma,
blastoid Variants of Burkitt's lymphoma Aggressive marginal zone lymphoma (monocytoid)

- General condition: General condition ECOG 0-3 (Karnofsky: 40 - 100 %); for definition
see Annex 14.10

- Presence of declaration of participation of the center and the patient's written
consent form

Exclusion Criteria:

- Prior mediastinal or extensive abdominal irradiation

- Prior high-dose therapy and autologous stem cell transplantation

- Impairment of renal function (creatinine > 2.5 mg/dL, creatinine clearance < 20
mL/min)

- Impairment of hepatic function (bilirubin > 2.0 mg/dL, cholinesterase [CHE] < 2000
U/L)

- Impairment of pulmonary function (transfer lung factor for CO [TLCO] < 50 %, forced
expiratory volume in 1 sec [FEV1] < 60 %, vital capacity [VC] < 60 %)

- Relevant deterioration of the above organ functions on salvage therapy

- Failure of stem cell mobilization

- Active viral hepatitis

- HIV infection

- Other active or not conclusively curatively treated malignoma

- Severe concomitant psychiatric illness or suspected lack of patient compliance

- Pregnancy or unreliable contraception

- Highly dynamic progress of lymphoma (lactate dehydrogenase [LDH] > 1.5 x upper limit
of normal [ULN]) after salvage therapy immediately prior to radioimmunotherapy