We examined the perioperative course of 1013 patients who had undergone coronary surgery between 1984 and 1987, to identify preoperative examination findings which are suitable as risk indicators in coronary surgery. The features we paid attention to were: anamnestic data, parameters of coronary disease, haemodynamic parameters and accompanying illnesses. We considered a perioperative course as complicated when systolic blood pressure dropped to 80 mmHg or less for longer than 15 min, when reconnection to the heart-lung-machine was necessary, when an intra-aortal balloon counterpulsation was required, when the patient had to have mechanical ventilation for longer than 24 h, when resuscitation took place, or when the patient died in the hospital. The Chi-square test was used for statistical analysis. Very good risk indicators (p less than 0.001) were: age greater than 60 y, resuscitation history, more than two bypass grafts, SvO2 70%, ejection fraction less than 50% and cardiac index less than 2.5 l/min*m2. Good risk indicators (p less than 0.001) were: functional capacity less than 50 watts, more than one previous myocardial infarction and LVEDP greater than 20 mmHg. LCA-stenosis, arterial hypertension with diastolic blood pressure values above 100 mmHg, and obstructive airway disease were identified as suitable risk indicators (p less than 0.05). The following findings were combined with significantly increased mortality: female sex, age over 60 years, two or more previous myocardial infarctions, history of resuscitation, mixed venous oxygen saturation below 70% and the need for three or more bypass grafts for complete revascularisation.