Atrial fibrillation (AF) is diagnosed for the first time in about 5 % of patients admitted for acute ischemic stroke. Advanced aged and arterial hypertension are risk factors for AF. We evaluated the prevalence of silent AF in subjects with advanced age and systemic arterial hypertension. Subjects of both gender, aged 65 years or more with systemic arterial hypertension were randomly identified from the patient lists of the participating general practitioners in the Perugia area, in Italy. Study subjects underwent baseline 12-lead ECG and, if this did not show AF, 48-h Holter monitoring was performed. AF was known and confirmed by 12-lead ECG in 4 out of the 308 evaluated subjects (1.3 %). Baseline 12-lead ECG showed no cases of silent AF. Holter monitoring was performed in 300 subjects, mean age 70 ± 4. Twenty-six recordings were not evaluable for the presence of artifacts; therefore, 274 subjects were included in the analysis. Holter monitoring showed AF in 27 out of 274 subjects (10 %; 95 % confidence interval 6.4-13.5 %); AF was longer than 30 s in four of the subjects. In 56 additional subjects, Holter monitoring revealed excessive supraventricular ectopic activity (20 %; 95 % confidence interval 15.3-24.7 %). Holter monitoring was able to detect silent AF in about 10 % of subjects aged 65 or above with systemic arterial hypertension. The risk of stroke associated with screened silent AF should be carefully evaluated.