The success rate of catheter recanalization of occluded coronary arteries is 50% to 80%. The reason for failure is frequently an occlusion which is to hard. As examples, two patients are reported with very hard coronary artery occlusions which were 5 months and 2 years old, respectively. There had been prior unsuccessful attempted treatment with other techniques. These occlusions could be recanalized with an 0.018 inch laser wire. Afterwards, a balloon dilatation could be carried out via the laser wire. The procedure was successful in both cases.