Inclusion Criteria:

- Relapsed or refractory follicular lymphoma grade I-II

- Tumor verified to be CD20 positive

- CT scan showing demarcated lesions

Exclusion Criteria:

- Previous treatment with rituximab resulting in less than partial response

- Previous radioimmunotherapy

- Previous stem cell transplantation

- Received the following treatments within 4 weeks prior to entering this study:

1. Anti-cancer therapy

2. Glucocorticosteroids unless less than 10 mg prednisolone/day

3. Radiotherapy

- Received Mitomycin C or Nitrosoureas within 6 weeks prior to entering this trial

- HIV positivity

- Hepatitis B or hepatitis C

- Uncontrolled or chronic bacterial, fungal or viral infection

- Other cancer diseases, except certain skin cancers, cervix cancer and breast cancer

- Certain serious medical conditions, including kidney or liver disease, some
psychiatric illnesses, and stomach, lung, heart, hormonal, nerve or blood diseases

- WHO performance status of 3 or 4

- If you are participating in another trial with a different new drug 4 weeks before
you enter this trial

- Current participation in any other clinical study

- Pregnant or breast-feeding women

- Women of childbearing age who are unable or unwilling to use an IUD or hormonal birth
control during the whole trial