The aim of our study was to evaluate the prevalence of asymptomatic episodes of ischaemia and their relation to heart rate in patients with effort angina pectoris undergoing continuous electrocardiographic monitoring for 24 h. We studied 91 patients with typical history of effort angina and positive stress testing (angina and rectilinear or downsloping ST segment depression more than 1 mm). During electrocardiographic monitoring 81 patients showed symptomatic or asymptomatic ischaemic episodes with ST segment depression, four patients a T wave inversion, while six patients did not show ischaemic episodes. The total number of ischaemic episodes registered was 284, of which 106 (37.32%) were symptomatic with significant heart rate increase, 130 (45.78%) asymptomatic with heart rate increase and 48 (16.9%) asymptomatic without heart rate changes. Twelve patients (13.18%) showed only symptomatic episodes of ischaemia with increase of heart rate, 26 patients (28.57%) symptomatic and asymptomatic episodes with heart rate enhancement, 12 patients (13.18%) only asymptomatic episodes with heart rate increase, eight patients (8.79%) symptomatic episodes of ischaemia with heart rate increase and asymptomatic ones with and without heart rate changes, and finally 23 patients (25.57%) showed symptomatic episodes with heart rate increase and asymptomatic ones without heart rate changes. In total, 31 (34.06%) of these patients showed during continuous electrocardiographic monitoring asymptomatic episodes of ischaemia without heart rate changes. These findings suggest a possible intervention of coronary tone modifications in determining asymptomatic ischaemic episodes without heart rate change in patients with effort angina.