A pharmaceutical composition comprising a camptothecin as active ingredient isherein described. In particular immediate-release therapeutic systems aredescribed for the improved oral absorption of 7-[(E)-t-butyloxyminomethyl]camptothecin, comprising a matrix consisting of liquid amphiphilic substancesor having a melting point lower than 60~C, in which the active principle is atleast partially dissolved and/or dispersed and/or inglobated.