Bismuth (III) subsalicylate, a commercial drug, was used as catalyst for 1,4-butanediol-initiated copolymerizations of epsilon-caprolactone (epsilon CL) and glycolide (GL). Telechelic copolyesters having two OH-endgroups and predominantly altemating sequences were obtained. These copolyesters are amorphous with glass transition temperatures (T(g)s) below -30 degrees C. In a second series of polymerizations, in situ chain extension with L-lactide (LLA) was performed, whereby A-B-A triblock copolymers were obtained without significant transesterification between A- and B-blocks. Finally, these A-B-A triblock copolymers were transformed into multiblock copolymers by chain extension with 1,6-hexamethylene diisocyanate. The block copolymers were characterized by H-1 and C-13 NMR spectroscopy, by viscosity, SEC and DSC measurements. (c) 2005 Elsevier Ltd. All rights reserved.