Biodegradable D,L-Lactide-epsilon-caprolactone copolymer was used in substitution to bovine collagen to seal porosity in nine Dacron vascular Sorin Carbografts. One served as control and 8 were implanted in mini-pigs as vascular by-pass in the thoracic aorta. The grafts were explanted at 7 days (4 animals), 30 (2 animals) and at 90 days (2 animals), and submitted to gross examination, X-ray, histology and electron microscopy. Aim of the study was to assess the safety and the reliability of these polyester vascular prostheses impregnated with the copolymer in terms of containment of the bleeding in the perioperative period, host inflammatory response, copolymer biodegradation and prostheses "healing" All the grafts were patent at angiographic and X-ray examination. At 7 days blood infiltration between Dacron and copolymer lining was detected. Inflammatory granulocyte infiltrates and granulomatous reaction with polymer degradation was observed at 30 days and fibrous tissue healing at 90 days. Luminal surface was covered by thin thrombi at 7 and by a neointima at 30 and 90 days. We conclude that D,L-Lactide-epsilon-caprolactone copolymer is effective in preventing perigraft bleeding, even though an early hematoma between Dacron and the copolymer coating occurs. Copolymer is degraded through a mild inflammatory reaction, with eventual evolution to fibrous healing.