A multicentre epidemiological study to detect the prevalence of myocardial ischaemia in hypertensive left ventricular hypertrophy (LVH) was performed in 188 asymptomatic male hypertensives (131 treated). The mean age was 55 (range 40-82) years with blood pressure (BP) > or = 160/100 mmHg or a systolic BP > or = 180 mmHg. The participants were screened with echocardiography, and left ventricular hypertrophy (LVH), defined as LV mass index (LVMI) > or = 130 g.m-2, was found in 127 (68%), of whom 95 were on antihypertensive treatment. Patients with LVH underwent a maximal bicycle ergometer exercise test and significant ST depression, indicating possible stress-induced ischaemia, was found in 29 men (23%). These subjects were subjected to exercise thallium-201 scintigraphy, which was normal in 14 but showed reversible perfusion defects in 15. Thus, a high prevalence of LVH (70%) was detected in male hypertensives selected only on age and BP. In addition, although chest pain on exertion excluded patients from entry, a substantial portion had signs of ischaemia (23% on exercise ECG alone, and in 52% confirmed by thallium scan). The prevalence of these risk factors should be considered when evaluating hypertensive patients.