Poly(p-dioxanone) (PPDO) samples with different molecular weights have been synthesized by the ring-opening polymerization of p-dioxanone. The thermogravimetric analysis of PPDO shows that the increase of molecular weights can improve the thermal stability of PPDO. The rheological property of PPDO with different molecular weights has been investigated using a Capillary Rheometer. The results show that PPDO exhibits a shear-thinning behavior; the apparent viscosity of melt increases with the molecular weight of PPDO and is very sensitive to temperature, decreasing sharply with the rise of temperature. In vitro degradation of PPDO films has also been carried out and excellent degradability has been found. The mechanical test shows that the tensile strength and modulus of PPDO increase with molecular weights. (C) 2004 Elsevier B.V. All rights reserved.