Methods of treatment using bendamustine formulations designed for small volume intravenous administration are disclosed. The methods conveniently allow shorter administration time without the active ingredient coming out of solution as compared to presently available formulations. The methods include parenterally administering a volume of about 325 ml or less of a liquid composition containing: a) from about 0.05 to about 12.5 mg/ml of bendamustine or a pharmaceutically acceptable salt thereof； b) a solubilizer comprising polyethylene glycol and propylene glycol； and optionally c) a parenterally acceptable diluent； over a substantially continuous period of less than or equal to about 30 minutes to a subject in need thereof.
