Bendamustine is a cytotoxic agent that combines alkylating and antimetabolite effects. It has shown promising efficacy in a number of hematological cancers and, hence, is being investigated in patients with chronic lymphocytic leukemia (CLL), which is the most common form of adult leukemia in the Western world. Phase I/II trials with bendamustine as single-agent therapy in CLL have shown overall response rates of 56-93% and complete response rates of 7-29%. Preliminary data from a Phase III trial comparing bendamustine and chlorambucil (an agent widely used in the current treatment of CLL) have shown significantly higher response rates with bendamustine. Bendamustine has also shown activity in CLL when combined with mitoxantrone, rituximab or both. The principal toxicities associated with bendamustine are hematological, mainly leukopenia.