Between June 1988 and November 1991, 64 out of 200 consecutive admissions (32%) before the 6th hour of myocardial infarction underwent angioplasty of first intention. Fifty men and 14 women (average age 62 +/- 11 years) benefitted from this 24 hour emergency interventional cardiology service. The indication was formal in 22% of patients because of a contra-indication to thrombolysis (N = 40) or cardiogenic shock (N = 4); in 6%, the choice was logical because of diagnostic uncertainty (N = 12); it was a deliberate choice in 4% of cases (N = 8). Successful angioplasty was defined as reperfusion of the occluded artery without circulatory delay or > 50% residual stenosis. Arterial recanalisation was attempted in all patients (associated with intraaortic balloon pumping in 3 cases) and was successful in 59 patients (92%) within 231 +/- 100 minutes of the onset of chest pain and within 49 +/- 29 minutes of hospital admission. The outcome was uncomplicated without any other intervention in 81% of patients (48/59). Three reocclusions were observed, two of which were symptomatic and treated successfully by repeat emergency angioplasty. Six surgical revascularisations were necessary (2 emergency, 4 secondary). One major complication related to the angioplasty was observed (haemopericardium). Global hospital mortality was 9% (6/64): three of the 4 patients admitted in cardiogenic shock, 3 of the 40 high risk patients with contra-indications to thrombolytic therapy, none of the 20 patients considered to be at low risk (uncertain diagnosis and deliberate choice).(ABSTRACT TRUNCATED AT 250 WORDS)