Poly(glycerol adipate) (PGA) is a biodegradable polymer with great potential for application in different drug delivery systems. The free hydroxyl group of the PGA backbone offers the possibility for various modifications and thus a flexible adaptation of its characteristics. In the present study, amphiphilic fatty acid modified PGA polymers were used, representing combined systems of polymer and lipids. The main part of this work deals with the preparation and comprehensive in vitro and in vivo characterization of nanoparticulate drug carriers of fatty acid modified PGA. The in vivo study particularly focuses on the tumor accumulation of the nanoparticles. The second part reports the application of Lauroyl-PGA in depot implants for controlled drug release. Besides various in vitro studies, the in vivo release of a lipophilic model drug was investigated in a 6-months pilot study.