Using thallium scintigraphy after a load (LTS), the authors tested suspected silent myocardial ischaemia (SIM) in subjects without angina pectoris. They examined 21 active pilots suspected of SIM after a previous ECG loading test (LET) and 33 patients with diabetes type I and II. In six pilots (28.6%) they found on LTS accumulation defects suggesting ischaemic disorders of the large coronary arteries. All except one had during submaximal load during LTS obvious depression of the ST segment on the ECG. Except one, in another five pilots small depressions of the ST segment were associated with normal LTS. Twelve diabetic patients (36.4%) had obvious minor accumulation defects on LTS. Only two had on the ECG a ST depression under 2 mm during LTS. Based on data in the literature suggesting a higher sensitivity and specificity of LTS, as compared with LET and the possibility of a false positive diagnosis of SIM from LET alone, the authors recommend when SIM is suspected to use also LTS. A more detailed diagnosis of SIM is essential not only with regard to the assessment of work capacity but also for the long-term follow-up of patients with SIM for assessment of its incidence, impact and prognosis in our population.