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