Objective:Cardiac index(CI) and mixed venous oxygen saturation SvO2 were studied in 85 patients undergoing coronary artery bypass grafting(CABG). Methods: Measurement of CI and SvO2 was carried out with a fiberoptic ballon-tip thermodilation pulmonary artery catheter. Fentanyl-based anesthesia was applied in all patients. Hemodynamic parame-ters were obtained prior to anesthesia induction as the baseline, after endotracheal intubation, after stemotomy, after weaning of cardiopulmonary bypass, at 6 and 24h after operation. Results: CI and SvO2 increased or was not changed at all time intervals, compared with the baselines. The changes of SvO2 correlated well with those of CI. Conclusion: The results suggest that continuous monitoring of SvO2 may be useful to predicting alteration in CI in patients undergoing CABG.