A very important goal of researchers today is providing poly(L-lactide) (PLA)-based polymers with controllable degradation profiles, various (soft or elastic) mechanical properties, reactivity for chemical modification, and other functionalities while keeping the favorable characteristics of PLA. This article concerns the synthetic methods and properties of the following novel lactide copolymers: (1) random and block copolymers of depsipeptide and L-lactide with reactive (ionic) side-chain groups, (2) comb-type PLA and branched PLA, and (3) PLA-grafted polysaccharide and PLA with terminal saccharide residues. Poly(depsipeptide-random-L-lactide)s and polydepsipeptide-block-poly(L-lactide)s with reactive (ionic) side-chain groups should be useful for the preparation of matrices and microspheres with reactive surfaces because of their amphiphilic structures. Comb-type PLA and branched PLA show lower crystallinities than linear PLA. PLA-grafted polysaccharide should be useful for the preparation of matrices with various microstructures and mechanical and degradation properties through the introduction of hydrophilic segments. (C) 2003 Wiley Periodicals, Inc.