Pulmonary function tests were measured in 33 male patients undergoing elective coronary artery bypass surgery. Three modes of surgical technique were used: Bilateral internal mammary artery graft (BIMA), single internal mammary artery graft (SIMA) and saphenous vein grafts (VS). Following parameters were recorded: patient's age, length, body weight, preoperative forced vital capacity (FVC) and forced expiratory volume at one second (FEV 1), preoperative end-diastolic pressure and function of the left ventricle, smoking habitus, the fact that the pleural cavity was entered, duration of the cardiopulmonary bypass period, perioperative fluid balance and postoperative FVC and FEV 1 on the first eight postoperative days. In the BIMA group two pleural cavities, the SIMA group one pleural sac and the VS group none of the pleural cavities was entered. The BIMA group was younger (50.1 +/- 7.6 versus 57.7 +/- 7.28 and 60.1 +/- 6.9 years (p less than 0.05)) than the SIMA and VS group. Postoperative external blood loss was lower in the VS group compared to the SIMA and BIMA groups (839 +/- 255 ml versus 1346 +/- 654 ml and 1259 +/- 396 ml (p less than 0.05)). The FVC shows a dramatic decrease especially on the second postoperative day and was most markedly diminished in the BIMA and SIMA compared to VS (31% +/- 9% and 35% +/- 8% versus 45% +/- 10% of preoperative values (p less than 0.05)).(ABSTRACT TRUNCATED AT 250 WORDS)