Liquid pharmaceutical formulation of Bendamustine that include bendamustine active pharmaceutical ingredient, N,N-Dimethylacetamide, and water in an amount of about 0.3% to 40%. The active pharmaceutical ingredient is Bendamustine, a pharmaceutically acceptable salt, and/or a hydrate form thereof, preferably Bendamustine HCl monohydrate. The formulations contain 20-200 mg/mL Bendamustine. The formulations are stable upon long term storage at refrigerated conditions. They can be administered to treat neoplastic conditions without reconstituting prior to administration.