Objective: We evaluated a bovine jugular vein graft with a natural trileaflet valve for right ventricular outflow tract reconstruction in a canine study for an entire year. Methods: Heparinized bovine jugular vein grafts with a natural valve cross-linked with a hydrophilic polyepoxy compound of 18 to 20 mm in internal diameter were implanted in the right ventricular–pulmonary arterial position in eight dogs, and the main natural pulmonary artery was ligated. Anticoagulants were not used after implantation. Five grafts were retrieved on day 182 after implantation and the other three grafts on days 196, 375, and 385, respectively, and were inspected by macroscopic and microscopic observation. Cardiac catheterization, followed by angiography and echocardiography, was done just before graft retrieval. Results: No graft kinking or regurgitation of the valve was observed. Echocardiography showed natural valve motion without thickening of the leaflets. Blood pressure in the conduits ranged from 18/9 to 31/4 mm Hg, in the right ventricle from 18/4 to 40/0 mm Hg, and the gradient varied from 0 to 14 mm Hg. The explanted conduits maintained their original shape, softness, and pliability with good coaptation of valves, without calcification or degenerative changes, except for one leaflet with slight deformation. In microscopic observation, endothelial cells lined the luminal surface of the conduit except for the areas adjacent to the valve. Conclusion: The graft worked perfectly as a right ventricular–pulmonary arterial valved conduit without anticoagulant therapy for a long time. J Thorac Cardiovasc Surg 1997;114:224-33