Background: Coronary artery bypass grafting (CABG) is associated with high morbidity in patients with chronic obstructive pulmonary disease (COPD). We examine the effect of preoperative systemic corticosteroids on morbidity in this setting. Methods: Ninety candidates for elective CABG participated in a prospective, open randomized trial, including 30 patients with COPD who received a single injection of a long-acting corticosteroid, 30 with COPD who received placebo, and 30 without COPD who served as controls. Primary end-points were postoperative pulmonary and nonpulmonary complications. Secondary end-points were length of hospital stay (LOS), ICU stay of less than 24 hours and more than 48 hours, duration of mechanical ventilation, and time to walking and sitting. Results: The rate of pulmonary complications was similar in the two COPD groups and in the COPD patients and controls. The placebo group had more major nonpulmonary complications than the treatment group, but the difference was not statistically significant (26% vs. 17%, P = NS). The non-COPD control group had significantly fewer nonpulmonary complications than the COPD patients (treatment+placebo) (33% vs 70%, P = 0.014) and a similar rate of pulmonary complications. There was a statistically significant difference between the treated and placebo COPD groups in ICU stay less than 24 hours (P ≤ 0.001) and more than 48 hours (P = 0.03) and hospital stay (P = 0.013). On stepwise analysis, only age and number of coronary grafts were predictors of pulmonary complications. Conclusion: The use of preoperative systemic corticosteroids in patients with COPD undergoing CABG may shorten ICU and hospital stay.