Background: The relationship between prolonged intubation period and postoperative complication incidence following cardiac surgery was investigated. Material/Methods: Evaluated were 237 adult patients who underwent coronary artery bypass graft operation, of whom 115 (group I) had intubation periods of more than 24 hrs (mean: 56.1±39.1 hrs) and 122 (group II) less than 24 hrs (mean: 16.25±14.6 hrs). Preoperative and postoperative pulmonary function test values as well as postoperative changes in the two groups were compared. Results: Mean hospital stay for group I and II patients were determined as 24.6±2.04 and 10.61±3.04 days, respectively (p<0.0001). The preoperative pulmonary function test results compared with the predicted values for both groups were similar. A significant decrease was determined in the postoperative pulmonary function test values in both groups, but the decrease in group I was significantly higher than in group II. Pulmonary complications developing in groups I and II were 26.09% (30 patients) and 7.38% (9 patients), respectively (p<0.0001). Also, total general complications were 39.14% (45 patients) and 13.12% (16 patients), respectively. Conclusions: Under similar conditions, the patients whose partial bypass time and aortic clamp period were signifi cantly longer needed to be ventilated for more than 24 hours, being related to late complications following bypass operation, and the complication risk of this group was 3.5 times higher than for those who remained intubated less than 24 hours. © Med Sci Monit.