This prospective observational study will evaluate the safety of MabThera/Rituxan (rituximab) in combination with chemotherapy in patients with previously untreated or relapsed/refractory B cell-lineage chronic lymphocytic leukaemia. Data will be collected from each patient for 6-12 months, depending on the prescribed chemotherapy regimen.

Inclusion Criteria:

• Adult patients, >/= 18 years of age
• B cell-lineage chronic lymphocytic leukaemia (B-CLL)
• Prescribed with MabThera/Rituxan in combination with chemotherapy according to the approved SMPC
• Informed consent to data collection

Exclusion Criteria:

• Treatment with any marketed or non-marketed drug substance or experimental therapy within 4 weeks prior to first dose of study drug or participation in a clinical trial within 30 days prior to entering this study
• Any other tumour disease

Patients with B cell-lineage chronic lymphocytic leukaemia (B-CLL)