Rituximab is FDA approved for the treatment of relapsed or refractory low grade or follicular CD20+ B cell non Hodgkin's lymphoma (375 mg/m(2) IV infusion once weekly for 4 or 8 doses). Recently, rituximab (anti CD20) has been introduced to CLL treatment regimens and has become an attractive choice in combination chemotherapy or as single agent treatment. Rituximab has been shown to be effective at lower doses than 375 mg/m(2) when given more frequently.