To develop guidelines for ranking the urgency with which patients with angiographically proven coronary disease need revascularisation procedures, factors that a panel of cardiac specialists agreed were likely to affect urgency were incorporated into 438 fictitious case-histories. Each panelist then rated the cases on a 7-point scale based on maximum acceptable waiting time for surgery; 1 on the scale represented emergency surgery and 7 delays of up to 6 months. For only 1% of cases was there agreement on a single rating by at least 12/16 panelists. Results of this ranking exercise were used by the panel to draw up triage guidelines. The three main urgency determinants were severity and stability of symptoms of angina, coronary anatomy from angiographic studies, and results of non-invasive tests for risk of ischaemia. Together these three factors generally gave an urgency rating for any given case to within less than 0.25 scale points of the value predicted with all factors. A numerical scoring system was derived to permit rapid estimation of the panel's recommended ratings.