The aim of the study was to investigate the mechanical properties and biodegradability of poly(trimethylenecarbonate-epsilon-caprolactone)-block-poly(p-dioxanone) [P(TMC-epsilon-CL)-block-PDO] in comparison with poly(p-dioxanone) and poly(glycolide-E-caprolactone) (Monocryl((R))) monofilaments in vivo and in vitro. P(TMC-epsilon-CL)-block-PDO copolymer and poly(p-dioxanone) were prepared by using ring-opening polymerization reaction. The monofilament fibers were obtained using conventional melt spun methods. The physicochemical and mechanical properties, such as viscosity, molecular weight, crystallinity, and knot security, were studied. Tensile strength, breaking strength retention, and surface morphology of P(TMC-epsilon-CL)-block-PDO, poly(p-dioxanone), and Monocryl monofilament fibers were studied by immersion in phosphate-buffered distilled water (pH 7.2) at 37 degrees C and in vivo. The implantation studies of absorbable suture strands were performed in gluteal muscle of rats. The polymers, P(TMC-e-CL)-block-PDO, poly(p-dioxanone), and Monocryl, were semicrystalline and showed 27, 32, and 34% crystallinity, respectively. Those mechanical properties of P(TMC-epsilon-CL)-block-PDO were comparatively lower than other polymers. The biodegradability of poly(dioxanone) homopolymer is much slower compared with that of two copolymers. (c) 2006 Wiley Periodicals, Inc.