Diminution of the "mini"-coil (G-A-W-coil) to a "micro"-coil makes more selective coil embolization possible in vessels down to 1.0 mm. in diameter. Application can be done by the 3.3-F-catheter for superselective embolization of a coaxial application set, consisting of a 7.6-F- and a 3.3-F-catheter. The very thin guide-wire 0.6 mm. in diameter serves as pusher as in other application sets too. In animal experiments 10 superselective embolizations are performed in the vascular system of the superior mesenteric artery in the small infestine of the dog. Vessel occlusion takes place in the same time as in the use of the "mini"- and the standard coil. No complications as coil dislocation or vessel perforation can be reported in the use of the "micro"-coil.