Ambulatory coronary arteriography was carried out in 160 patients in the first 18 months' activity of our department (9.5% of all cardiac catheterisations and 16% of all coronary arteriographies during the same period). An absolutely stable clinical condition was the main criterion of selection for this investigation and the protocol consisted in day hospital admission, absence of routine anticoagulation, small calibre (5 French = 1.7 mm) catheters, mobilisation 4 hours and discharge 6 hours after the procedure. The patients were 38 women and 122 men whose average age was 55 years. The percutaneous femoral approach was used in most cases (95%). Single or multiple coronary artery disease was documented in 55 per cent of these patients: there were 2 cases of left main stem stenosis. Eight patients required full hospital admission, mainly because of the severity of the coronary lesions. Minor complications occurred in 2 per cent of cases. These results indicate that ambulatory coronary arteriography is safe, effective and economic. It could be used more extensively always providing that the contra-indications are respected.