The incidence of postoperative myocardial infarction (MI) is proportional to the incidence of myocardial ischaemic episodes. Therefore, the prevention of such episodes is of great clinical importance. METHODS. In 90 patients undergoing coronary artery bypass grafting (CABG), perioperative i.v. treatment with either nitroglycerin (NTG), diltiazem (DIL), or the combination of DIL/NTG was used until arrival in the intensive care unit. Myocardial ischaemic episodes were monitored with an automatic ECG-ST-trend analyser (Marquette 7010). RESULTS. Significantly less ischaemic episodes were seen in the DIL group (6.7%) compared to the NTG group (13.2%) or DIL/NTG group (13.5%). Furthermore, significantly less ischaemic episodes were associated with relevant haemodynamic alterations in the DIL group (58.1%) compared to the NTG (89.1%) or DIL/NTG group (80.0%). Increases in heart rate were markedly reduced in the DIL group. DISCUSSION. DIL results in marked haemodynamic stabilisation during CABG, especially in the period immediately after extra-corporeal circulation. This might serve as an explanation for the significant reduction in ischaemic episodes in the DIL group compared to the other two groups. Therefore, perioperative prevention of myocardial ischaemia with the calcium antagonist DIL seems to be favourable in patients during CABG.