The presence of ST-segment depression during ambulatory electrocardiographic monitoring, in relation to blood pressure treatment and control, was monitored in a non-randomized study in 167 men (49%) from the ‘Men born in 1914’ Malmö study, who were considered to have hypertension (diastolic blood pressure [DBP], ≧ 95 mm Hg or receiving antihypertensive therapy). Men were excluded if they had a history of ischemic heart disease. A high frequency of ST-segment depression (41%) and associated high cardiac event rate (14%) were found in hypertensive elderly men who had inadequately controlled blood pressure (i.e. DBP > 95 mm Hg). This was associated with a relative risk of a cardiac event of 9.8 (95% confidence interval: 2.6-36.9), even after adjustment for smoking, blood lipids and alcohol consumption. The lower frequency of ST-segment depression (21%) and lower cardiac event rate (5%) in hypertensive men with adequate blood pressure control suggests that effective antihypertensive treatment leads to a reduced event rate. In conclusion, the occurrence of ST-segment depression during ambulatory electrocardiographic monitoring in this group of subjects may be an expression of silent myocardial ischemia, with or without left ventricular hypertrophy. The incidence of asymptomatic ST-segment depression and the rate of cardiac events in hypertensive patients may be, in part, related to the level of blood pressure control attained.