The ring-opening polymerization of a novel heterocyclic monomer of the 1,4-dioxane 2,5-dione type, namely 3-(1,2-3,4-tetraoxobutyldiisopropylidene)dioxane-2,5-dione (DIPAGYL), derived from glycolic acid and partially protected gluconic acid, was investigated. Polymerization of DIPAGYL was carried out in the presence of either stannous octoate or antimony trifluoride. The influence of several factors on the polymerization yield and on the molecular weights of the resulting polymers was evaluated using an experimental design. The polymers obtained in the presence of antimony fluoride (polyDIPAGYL-Sb) and stannous octoate (polyDIPAGYL-Sn) had different microstructures according to the distribution of sequences of repeat units as determined by H-1 NMR. The main chain of polyDIPAGYL-Sb was primarily composed of alternating g (gluconic) and G (glycolic) units. In contrast, the polymer chain of polyDIPAGYL-Sn resulted from a random distribution of the two comonomer units. The isopropylidene groups which protected the side chain alcohol groups in polyDIPAGYL chains were partially cleaved by acid hydrolysis to yield hydroxyl-bearing hydrolytically degradable polyesters.