This study aimed to investigate the effects of planned respiratory cares and Continuous Positive Airway Pressure (CPAP) on atelectasis and arterial blood oxygen levels in Coronary Artery Bypass Graft (CABG) patients. pulmonary complications and oxygenation impairment after Coronary Artery Bypass Surgery (CABS) are prevalent and lead to increased hospitalization and treatment costs. Planned respiratory cares and the application of ventilation with CPAP mode are among the proceedings that are conducted in most of the health centers, but there are not sufficient scientific evidences to confirm the effectiveness of one of these proceedings after CABS. The preset study was a three-group clinical trial with the sample size of 120 patients (40 patients in each group) candidate for CABG based on permuted-block randomization. This study was conducted at ShahidRajaei Hospital, Iran in 2015. Patients in experimental group (1) received planned respiratory cares; patient in experimental group (2) received noninvasive ventilation with CPAP mode and; patients in control group received conventional respiratory cares. Other treatments were similar for all three groups. The groups of interest were compared regarding the percentages of measured arterial oxygen saturation before surgery and days one, two, and three after surgery. Also, chest X-rays of patients both before and after surgery (day 3) were compared in terms of atelectasis. Data were analyzed by SPSS 16 using Chi-square tests, Kruskal- Wallis, and Friedman. the results showed that there is not any significant difference between three groups in terms of demographic variables, disease background, and arterial oxygen saturation values before surgery. In day (1), before intervention in patients of group 3, the arterial oxygen saturation values were higher compared to other two groups (p=0.03) and (p=0.001). In the case of atelectasis incidence, patients in group 2 had lowest incidence rate compared to other groups. However, there was no significant difference between three groups of the study. the results of this study showed that those patients who received noninvasive ventilation with CPAP mode after surgery, have better oxygenation status compared to patients receiving planned respiratory cares and patients receiving conventional cares. Also, oxygenation and recovery procedures are faster in these patients. The incidence of atelectasis in this group is lower compared to other groups. Therefore, it is recommended to use this noninvasive method to have better ventilation for patients under open heart surgery.