Novel biodegradable copolymers of 5-methyl-5-methoxycarbonyl-1,3-dioxan-2-one (MMTC) and caprolactone (CL) were synthesized under different conditions by ring-opening polymerization. The structure of the resultant copolymers was characterized by IR, H-1 NMR and C-13 NMR methods. Their molecular weight was measured by gel permeation chromatography (GPC). Incorporating the MMTC units into PCL main chain results in the great enhancement of hydrolytic degradation rate and the effective retardance of release rate of Tegafur in comparison with the PCL homopolymer. The enzymatic degradation rate increases with increasing the molar content of PCL, and the copolymers degrade faster in the presence of pseudomonas (PS) lipase than that in the absence of PS lipase. Some mechanical properties of the copolymers were tested and showed that they can be adjusted by varying the composition of the copolymers. (c) 2005 Elsevier Ltd. All rights reserved.