[en] Background. Cardiac surgery is followed by various degrees of inflammation, which have harmful consequences. Because of the central role of extracorporeal circulation ( EC), off- pump coronary bypass surgery is deemed preferable. Do different modalities of EC challenge this view? Methods. Four groups of similar patients underwent coronary surgery: ( group 1) on- pump, EC with closed surface modifying additives ( SMA) circuit and no pump suckers ( n = 20); ( group 2) on- pump, EC with open SMA circuit and pump suckers ( n = 20); ( group 3) off- pump ( beating heart) and heparin 3 mg/ kg ( n = 20); ( group 4) off- pump ( beating heart) and heparin 1 mg/ kg ( n = 20). Interleukins ( IL)- 6, IL- 8, IL- 10, myeloperoxidase, elastase, and terminal complex of the complement ( TCC) were analyzed at various times: at induction ( time I); after heparin ( time II); after complete revascularization ( time III); after protamine ( time IV); and 24 hours later ( time V). Results. The TCC was significantly higher in groups 1 and 2 at time III. The pattern of IL- 6 was the same for the four groups. No significant difference in myeloperoxydase content was noted; however, elastase was significantly higher in the two EC ( on- pump) groups. Conclusions. Except for the complement system and elastase, on- pump surgery with SMA- coated circuits did not elicit any greater inflammatory response than off-pump surgery.