Inclusion Criteria:

- Pathologically verified primary central nervous system lymphoma No prior PCNSL
treatment.

- Patients treated with steroids alone are eligible

- No signs of lymphoma outside the CNS

- ECOG performance status 0-4

- Age > 17 and < 76 years

- Written informed consent from the patient or guardian

Exclusion Criteria:

- Cardiac failure > 3

- Pregnancy or lactation. Women of childbearing potential are requested to use an
effective method of contraception to avoid pregnancy for a period from entry to the
study and at least 3 months after the last study medication

- Previous malignancy unless disease free for at least five years

- Active infection.

- Regarding tuberculosis, patients at risk should be tested for latent TB according
local practice at each treating centre.

- Positive HIV status

- Organ transplantation

- Serious psychiatric illness

- Prior radiotherapy to the brain

- Concomitant anti-inflammatory medication that cannot be discontinued

- Creatinine clearance < 60 ml/minute calculated by Cockcroft and Gault formula

- Peripheral blood count with granulocytes <1.5 x 109L or platelets < 100 x 109L

- Serum bilirubin >1.5 times or ASAT and alkaline phosphatase >2 times upper limits of
normal.

- Known anaphylaxis or IgE-mediated hypersensitivity to murine protein or any component
of Rituximab excludes patients from Rituximab treatment, but not from the remaining
part of the study