The role of pre-operative short-term pulmonary rehabilitation in patients with chronic obstructive pulmonary disease who undergo coronary artery bypass graft surgery has been assessed for the first time prospectively. Forty-five patients posted for coronary artery bypass graft surgery were randomised to receive either short-term pulmonary rehabilitation (group I) or no such programme (group II). Patients of both the groups were evenly matched with respect to age, sex, body surface area, duration and severity of chronic obstructive pulmonary disease and coronary artery disease. Normal individuals who evenly matched with the study group were assessed for normal respiratory function parameters. Pre-operative and post-operative peak expiratory flow rate, inspiratory capacity, post-operative ventilation time, post-operative pulmonary complication and hospital stay were determined in both the groups. Peak expiratory flow rate (220.0 +/- 12.9 and 324.3 +/- 84.3 in group I, 218.0 +/- 16.4 and 260.5 +/- 35.2 in group II) and inspiratory capacity (844.0 +/- 147.4 and 1100.0 +/- 158.1 in group I, 830.0 +/- 117.4 and 1090 +/- 137 in group II) were significantly lower before and after surgery respectively in both groups compared to normal values. Even though both groups showed a significant rise in post-operative peak expiratory flow rate and inspiratory capacity after surgery, the post-operative peak expiratory flow rate and inspiratory capacity in group I was significantly higher than in group II. In group I, the post-operative ventilation time (24.5 +/- 6.00 hours), post-operative complications (n = 4) and hospital stay (12.4 +/- 3.6 days) were significantly lower than in group II (35.2 +/- 22.3 hours, n = 11, 18.8 +/- 6.6 days respectively). These data suggest that short-term pulmonary rehabilitation is feasible and effective in improving pulmonary functions before and after surgery and in reducing surgical morbidity and cost of medical care significantly.