The purpose of thee present work is to compare th value of two non invasive techniques: cycloergometer and dynamic ECG (Holter) in the diagnosis of ischaemic heart disease in subjects without basal ECG abnormalities and without clearcut clinical signs of coronary insufficiency. Twenty patients underwent both tests while in hospital. The ECG was continuously monitored for 24 hours according to the Holter method. In fifteen out of the twenty cases examined for results obtained with the two different techniques were in agreement; in three cases ischaemic ECG changes were seen only with the ergometer, in one only with the Holter and in one they were clearly present with the Holter, but were doubtful with the ergometric test. In our experience the Holter method should represent the first approach to studying patients suspected to be suffering from angina pectoris in view of its good sensitivity and of the absence of risk and contraindications. Maximal exercise test should be reserved to the patients in whom the Holter method has given negative results. The latter not only has a diagnostic value, but also "quantifies" the degree of ischaemia by recording symptomatic and asymptomatic ST depressions.