✓ Bypasses of the sagittal sinus, 2.5 mm in diameter, were carried out in 25 dogs with venous (13 cases) and arterial (12 cases) autogenous grafts, by classical microtechniques. Animals were sacrificed 10 to 75 days after the operation, average 40 days. The patency rate was 54% in the venous autograft group; in all cases, thrombosis occurred early and was due to technical factors. The immediate postoperative patency rate was 100% in the arterial graft group, but this type of graft showed a tendency to progressive occlusion because of extensive fibrosis of the arterial wall; thus the patency rate was 75% at the time of autopsy. This preliminary work demonstrates the technical feasibility of bypass procedure which could be used for sagittal sinus repair.