Introduction: The application of non-invasive ventilation(NIV) after coronary artery bypass grafting(CABG) brings the possibility of reducing loss of functional capacity and complications in the patient. However, the evidence is controversial about immediate or conventional use. Objective: Assess the impact of immediate NIV after extubation on oxygenation and functional capacity of patients undergoing to CABG. Methods: Randomized clinical trial. Patients were assessed before and after surgery using the Functional Independence Measure(FIM), six-minute walk test(6MWT) and peripheral muscle strength(MRC). On the first day after the surgery, two groups formed immediate NIV(NIVI) and conventional NIV(NIVC). Hemogasometry was collected before and after NIV. Complication rates were also assessed. NIVI performed ventilation after one hour of orotracheal extubation, at NIVC performed NIV on the first postoperative day, 24 hours after extubation. After discharge, the above variables were reevaluated. Results: 79 patients were evaluated, 46(58.22%) men, mean age 65±9 years. NIVI reduced the reintubation rate, only 1 (3%) compared to NIVC with 5 (12%) patients, p=0.01. In the post-Intervention the inspired oxygen fraction (FiO2) was 0.43±0.07 in the conventional group and 0.30±0.10 in the intervention group, p=0.01. The post-intervention PaO2/FiO2 ratio was 191±45 and NIVI 266±29(p <0.001) and one day later in the NIVC it was 210±39 and NIVI 279±37(p <0.001). VNII lost 51±36 meters in the 6MWT compared to the NIVC that lost 95±40 meters(p <0.01). Conclusion: NIVI after extubation of patients undergoing to CABG, reduced the loss of functional capacity, improved blood gases and decreased the rate of reintubation.