Abstract We developed a new bio-absorbable polymeric coil, Matrix, to improve biological reaction of the current Guglielmi detachable coil (GDC) system. This new coil can accelerate histopathologic transformation of unorganized clot into fibrous connective tissue. As a preliminary study, we tested Matrix coil in 16 experimental aneurysms created in eight swine. For each animal, one aneurysm was embolized with Matrix coil and the other with GDCs. Comparative angiographic and histopathologic data were analyzed at 2 weeks after embolization. At 14 days, bio-absorbable coil, Matrix, accelerated aneurysm fibrosis and proliferation of neck neointima without causing parent artery stenosis. Matrix coil may improve long-term anatomical outcome of standard GDCs by decreasing aneurysm recanalization due to accelerated organized fibrous tissue.