Haemodynamic parameters and coronary sinus (CS) flow were studied perioperatively in 19 coronary artery bypass graft (CABG) patients. After sternotomy, the heart rate increased. Compared to just before extracorporeal circulation was commenced, the cardiac index (CI) increased from 2.3±0.14 to 3.11±0.14 l/M2 and CS flow from 104±10 to 149±9 ml/min. The systemic vascular resistance (SVRI) decreased from 2,430±139 to 1,628±91 dyne.sec.cm-5. During transport to the intensive care unit (ICU) the central venous pressure (CVP) decreased from 11±1 to 5±0.5 mmHg, the pulmonary artery wedge pressure (PAWP) from 14±0.8 to 8±0.5 mmHg, the CI from 2.79±0.08 to 2.32±0.11 l/M2, CS flow from 162±11 to 132±12 ml/min, myocardial lactate uptake from 33.7 to 13.6 µmol/min, skin temperature from 33.3°C to 30.1°C, and rectal temperature from 36.3°C to 34.9°C. These haemodynamic changes occurred despite volume loading of 22±2.3 ml/min before transport. The SVRI increased from 1,848±116 to 2,324±128 dyne.sec.cm-5 after transport. In the ICU the CI increased to 3.03±0.18 l/min due to a decrease in SVRI to 1,849±99 dyne.sec.cm-5 and an increase of heart rate to 91±3 bpm. The stroke volume index (SVI) remained decreased compared to preoperative levels. We conclude that major haemodynamic changes occurred on transferring the patient from the operating room to the ICU with decreased filling pressures (CVP, PAWP) together with a decrease in CI, CS flow and temperature. This, in combination with myocardial depression following aortic declamping and cardioplegia, can endanger myocardial perfusion and thus recovery after CABG. Care should be taken to avoid changes in filling pressures and temperature.