Disclosed herein is a pharmaceutical composition for oral administration, the composition comprising bendamustine (4-[5-[bis(2-chloroethyl)amino]-1-methylbenzimidazo-2-yl]butanoic acid, a nitrogen mustard) or a pharmaceutically acceptable, ester, salt or solvate thereof as an active ingredient, and a pharmaceutically acceptable excipient, which is a pharmaceutically acceptable non-ionic surfactant, selected from the group consisting of macrogol glycerol hydroxystearate, polyoxyl- 35- castor oil and ethylene oxide/propylene oxide block copolymer.
