As part of the search of novel degradable polymers, amphiphilic and cationic poly(is an element of-caprolactone)-g-poly(L-lysine) (PCL-g-PLL) copolymers have been synthesized following a grafting "onto" or a grafting "from" method both applied to a macropolycarbanionic PCL derivative. The first approach led to PCL-g-PZLL containing 36% of E-caprolactone and 64% of N-epsilon-Z-L-lysine units, by reaction of activated poly(N-epsilon-Z-L-lysine) on the macropolycarbanion derived from PCL. The second route was based on the anionic ring opening polymerization of N-carboxyanhydride of N-epsilon-benzyloxycarbonyl-L-lysine initiated by the macropolycarbanion derived from PCL and led to a similar copolymer containing 45% of of E-caprolactone and 55% of N-epsilon-Z-L-lysine units. After deprotection of the lysine units, PCL-g-PLL copolymers were obtained. These copolymers are water-soluble and form nanometric micelle-like objects with mean diameters between 60 and 500 nm in distilled water depending on the synthesis route.