Lund University Cardiopulmonary Assist System (LUCAS) is a new gas-driven CPR device providing automatic chest compression and active decompression. This is a report of the first 100 consecutive cases treated with LUCAS due to out-of-hospital cardiac arrest (58% asystole, 42% ventricular fibrillation (VF)). Safety aspects were also investigated and it was found that LUCAS can be used safely regarding noise levels and oxygen concentrations within the ambulance. A crash test (10G) showed no displacement of the device from the manikin. Of the 71 patients with witnessed cardiac arrest, 39% received bystander CPR. In those 28 patients where LUCAS-CPR was initiated more than 15 min after the ambulance alarm and in the 29 unwitnessed cases, none survived for 30 days. Of the 43 witnessed cases treated with LUCAS within 15 min, 24 had VF and 15 (63%) of these cases achieved a stable return of spontaneous circulation (ROSC) and 6 (25%) of them survived with a good neurological recovery after 30 days; 5 (26%) of the 19 patients with asystole achieved ROSC and 1 (5%) survived for over 30 days. One patient where ROSC could not be achieved was transported with on-going LUCAS-CPR to the catheter laboratory and after PCI for an occluded LAD a stable ROSC occurred, but the patient never regained consciousness and died 15 days later. To conclude, establishment of an adequate cerebral circulation as quickly as possible after cardiac arrest is mandatory for a good outcome. In this report patients with a witnessed cardiac arrest receiving LUCAS-CPR within 15 min from the ambulance call had a 30-day survival of 25% in VF and 5% in asystole, but if the interval was more than 15 min, there were no 30-day survivors.