BACKGROUND: Silent brain infarcts are detected by neuroimaging in up to 20% of asymptomatic patients based on population studies. They are five times more frequent than stroke in general population, and increase significantly both with advancing age and hypertension. Moreover, they are independently associated with the risk of future stroke and cognitive decline.Despite these numbers and the clinical consequences of silent brain infarcts, their prevalence in Mediterranean populations is not well known and their role as predictors of future cerebrovascular and cardiovascular events in hypertensive remains to be determined.ISSYS (Investigating Silent Strokes in Hypertensives: a magnetic resonance imaging study) is an observational cross-sectional and longitudinal study aimed to: 1- determine the prevalence of silent cerebrovascular infarcts in a large cohort of 1000 hypertensives and to study their associated factors and 2-to study their relationship with the risk of future stroke and cognitive decline. METHODS/DESIGN: Cohort study in a randomly selected sample of 1000 participants, hypertensive aged 50 to 70 years old, with no history of previous stroke or dementia.On baseline all participants will undergo a brain MRI to determine the presence of brain infarcts and other cerebrovascular lesions (brain microbleeds, white matter changes and enlarged perivascular spaces) and will be also tested to determine other than brain organ damage (heart-left ventricular hypertrophy, kidney-urine albumin to creatinine ratio, vessels-pulse wave velocity, ankle brachial index), in order to establish the contribution of other subclinical conditions to the risk of further vascular events. Several sub-studies assessing the role of 24 hour ambulatory BP monitoring and plasma or genetic biomarkers will be performed.Follow-up will last for at least 3 years, to assess the rate of further stroke/transient ischemic attack, other cardiovascular events and cognitive decline, and their predictors. DISCUSSION: Improving the knowledge on the frequency and determinants of these lesions in our setting might help in the future to optimize treatments or establish new preventive strategies to minimize clinical and socioeconomic consequences of stroke and cognitive decline.