Background: The efficacy of nasal continuous positive airway pressure (nCPAP) as a prophylactic method for preventing cardiopulmonary complications after major vascular surgery has not been investigated. Patients/methods: In a prospective randomized trial, 204 patients undergoing elective midline laparotomy for vascular surgery were randomized to receive standard therapy (n=105) or additional prophylactic nCPAP (n=99) for the first postoperative night. Postoperative oxygenation, incidence of severe cardiac, and pulmonary complications, length of intensive care surveillance and length of total postoperative hospital stay (LOS) were compared. Results: Prophylactic nCPAP significantly reduced the number of patients with severe oxygenation disturbances defined as paO₂<70 mmHg with FiO₂S 0.7 (5 versus 17, P=.01). There were no differences with respect to death, cardiac and pulmonary complications, length of intensive care surveillance or LOS. Conclusion: Prophylactic 12 h nCPAP significantly reduces the occurrence of postoperative oxygenation disturbances but has no effect on cardiac or pulmonary complications, need for intensive care, LOS or mortality after major vascular surgery.