Cardiopulmonary bypass triggers systemic inflammation and systemic oxidative stress. Recent reports suggest that continuous ventilation during cardiopulmonary bypass (CPB) can affect the outcome of patients after cardiac surgery. We investigated the influence of lung ventilation on inflammatory and oxidative stress markers during coronary artery bypass graft (CABG) with CPB in 13 patients with (Group 2) or without (Group 1) ventilation of the lungs with small tidal volume (4 ml/kg). IL-10 and elastase in blood were elevated in both groups with a peak at the end of CPB (P<0.05) and returned to the baseline at 24 h after surgery. A significant increase in Trolox Equivalent Antioxidant Capacity (TEAC) was observed in both groups (P<0.05). Glutathione peroxidase (GPx) was significantly elevated 24 h after surgery only in Group 1 (P<0.05). There was a significant decrease in alpha-tocopherol 24 h after surgery in both groups (P<0.05). The inflammatory response observed during CPB is not directly influenced by continuous ventilation of the lungs with small tidal volumes. The modulation of antioxidant defense systems by ventilation needs further investigation.