First clinical experiences in the treatment of chronically occluded arteries with 7F-multi-fiber catheter systems transmitting pulsed laser light are presented. 16 patients (7 stadium IIb, 4 stadium III, 5 stadium IVa Fontain) underwent the procedure. 14 of 16 lesions (distance: 0.5-10 cm), most of them with visible calcification, could be recanalized successfully. After the catheter had passed lesions several times, remaining stenoses of 48% (mean value) could be reduced by balloon angioplasty. By moving the catheter with less speed than the experimentally determined speed of laser light ablation and by guiding it over a safety wire, perforation and embolization could be avoided. In one case, occlusion material was pressed into collateral vessels and in two cases groin hematomas had to be observed.