The aim of this study was to estimate the incidence of silent myocardial ischaemia in patients with mild to moderate hypertension, white-coat hypertension (WCH) and those with normal blood pressure, Ambulatory electrocardiographic (ECG) monitoring was carried out in 272 cases with normal blood pressure, 164 cases with mild to moderate hypertension (diastolic blood pressure >95 and <114 mm Hg), and 106 cases with white-coat hypertension who were diagnosed with ambulatory blood pressure monitoring. The ages of the patients of all groups were between 42-61 years, There were no differences between the groups according to age, gender and other parameters, There were no anginal symptoms, and resting ECGs were in normal limits in all cases. The diagnosis of silent ischaemia was considered to be present if there was ST depression >2 mm/at least 120 sec in ambulatory ECG examination without angina or its equivalent cardiac symptoms. The incidence of silent ischaemia was 6.4%, 18.8%, and 26.2% in cases with normal blood pressure, WCH, and hypertension, respectively. The differences between groups were significant. It was concluded that WCH is not a benign condition, but shares some characteristics with essential hypertension.