The use of B cell depletion as a mode of treatment for non-Hodgkin's lymphoma was first utilized in 1997 when Rituximab, a chimeric human-mouse monoclonal antibody which has a high affinity to the CD20 antigen expressed on B cells, became available. Over 500000 lymphoma patients have been treated worldwide with this drug and it has a good safety record. The notion that B cells might be critical to the development of rheumatoid arthritis led to the extension of the use of B cell depletion to this condition and a recent double blind controlled trial has shown very encouraging results. In addition, B cell depletion either using Rituximab alone, or in combination with cyclophosphamide and corticosteroids has also been reported to have been of great benefit in some patients with severe systemic lupus erythematosus albeit in open label studies. This review considers the mechanism of action of the drug, the clinical trials that have been reported, and tries to place its current use in patients with autoimmune rheumatic disease in context.