OBJECTIVE To more fully define the influence of COPD in patients undergoing coronary artery bypass grafting (CABG). METHODS One hundred ninety-one patients with COPD underwent CABG from March 1, 1995, to June 21, 1996. There were 129 male and 62 female patients. The mean age was 69 years (45 to 86 years). Patients with COPD were defined according to the Summit Database definition: requires therapy for the treatment of chronic pulmonary compromise or has an FEV1 <75% of predicted value. RESULTS Hospital mortality was 7%. Hospital morbidity was 50%. Statistically significant (p<0.05) morbidity included general pulmonary complications (12%) and atrial fibrillation (27%). Hospital mortality for COPD patients with postoperative pneumonia was 11%. Hospital mortality for patients with COPD receiving steroids was 19%. The hospital mortality for patients > or = 75 years of age was 17%. The combined mortality for patients with COPD who are > or = 75 years of age and receiving steroid therapy was 50%. The mean length of stay was 12 days. Late mortality was 1% at a mean of 1.5 years. CONCLUSIONS Hospital mortality in most patients with mild-to-moderate COPD undergoing CABG is similar to those without COPD. In the minority of patients with severe COPD who are receiving steroids and > 75 years, the hospital mortality is exceptionally high. These findings support CABG in patients with mild-to-moderate COPD. Nonsurgical therapy should be considered for elderly COPD patients with severe disease taking steroids.