Background <p>In autologous vein bypass surgery, a&#xa0;distinction must be made between early postoperative bypass occlusion following initial bypass placement and late-onset occlusion with acute clinical symptoms.</p> Objective <p>To describe the approach to restoring bypass function in cases of early postoperative occlusion and late-onset occlusion of an autologous vein bypass.</p> Material and methods <p>In early postoperative occlusion mechanical factors are usually the primary cause. These must be identified and eliminated. Thrombectomy should be performed with extreme care to avoid a further increase in the already existing risk of developing bypass graft stenosis. Suboptimal vein segments should be discarded during revision and replaced with higher quality autologous vein material. Incorrect bypass positioning must be corrected. In late-onset occlusion progressive degeneration of the vein bypass and deterioration of arterial outflow due to the progression of the underlying arterial disease should be considered as likely causes. Degeneration is often only detected during emergency diagnostic imaging in cases of new ischemia. In cases of routine bypass follow-up, bypass or anastomotic stenosis or aneurysmal dilatation is already known. In an acute occlusion restoration of bypass function must be accompanied by correction of the mechanical cause.</p> Results and discussion <p>There is no standardized approach for the treatment of acute venous bypass occlusion but an individualized solution must be found based on the specific circumstances.</p>