The influence of cytokines on the inflammatory response in surgery has recently been the subject of investigations. We measured tumor necrotic factor-alpha (TNF-alpha), interleukin 1 beta (IL-1 beta), interleukin 6 (IL-6), interleukin 8 (IL-8), and granulocyte elastase (GEL) in 26 patients undergoing elective cardiac operations using cardiopulmonary bypass (CPB), preoperatively, immediately after CPB, and on post-operative days (PODs) 1, 3, and 6. To evaluate the effect of these cytokines on pulmonary function, the patients were divided according to whether the oxygenation index (OI) on POD 1 was > 250 or < 250, into groups A and B, respectively. TNF-alpha and IL-1 beta were undetectable and there were no significant differences in the preoperative IL-6, IL-8, and GEL levels. However, immediately following CPB, the mean IL-6, IL-8 and GEL levels in both groups were significantly higher than the preoperative levels (P < 0.01). Moreover, all these levels were significantly higher in group B than in group A, at 162 +/- 150 pg/ml vs 64 +/- 53 pg/ml (P < 0.05) for IL-6; 53 +/- pg/ ml vs 22 +/- 20 pg/ml (P < 0.01) for IL-8; and 2477 +/- 1642 mg/ l vs 1397 +/- 774 mg/l (P < 0.01) for GEL. The IL-6 levels returned to the preoperative values in both groups on POD 1; however, the GEL levels remained significantly higher in group B than in group A postoperatively, at 616 +/- 326 mg/l vs 378 +/- 70 mg/l on POD 1, and at 292 +/- 70 mg/l vs 218 +/- 62 mg/ l on POD 3 (P < 0.05). Thus high levels of cytokines such as IL-6, IL-8, and GEL may be detrimental to respiratory function.