The invention concerns novel materials based on biodegradable branched polyaminoacids particularly useful for transporting active principle(s). The invention also concerns novel pharmaceutical, cosmetic, dietetic or phytosanitary compositions based on polyaminoacids. The invention aims at providing a novel polymeric material, capable of being used for transporting active principle(s) and enabling all the required relevant specifications to be optimally satisfied: biocompatibility, biodegradability, easy ability to be combined with a large number of active principles or to solubilize same, and to release the active principles in vivo. This is achieved by the present invention which firstly concerns branched polyaminoacids comprising aspartic acid units and or glutamic acid units, and which bear hydrophobic groups including 8 to 30 carbon atoms. The branched polyaminoacids are amphiphilic and are capable of being easily and economically transformed into particles for transporting active principles, the particles being themselves capable of forming stable aqueous colloidal suspensions.