IntroductionFamilial hypercholesterolaemia (FH) is the most common monogenic autosomal dominant genetic disorder and is associated with a high risk of premature atherosclerotic cardiovascular disease. The prevalence of FH has been reported to be particularly high in certain founder populations. The population of the Faroe Islands is a founder population, but the prevalence of FH has never been investigated here. We aim to assess the prevalence of FH and to describe the genetic and clinical characteristics and potential causes of FH in the Faroe Islands. Furthermore, we aim to investigate whether indicators of subclinical coronary artery disease are associated with FH.Methods and analysisThe prevalence of FH will be estimated based on an electronic nationwide laboratory database that includes all measurements of plasma lipid levels in the Faroe Islands since 2006. Subsequently, we will identify and invite subjects aged between 18 and 75 years registered with a plasma low-density lipoprotein cholesterol above 6.7 mmol/L for diagnostic evaluation. Eligible FH cases will be matched to controls on age and sex. We aim to include 120 FH cases and 120 controls.Detailed information will be collected using questionnaires and interviews, and a physical examination will be undertaken. An adipose tissue biopsy and blood samples for genetic testing, detailed lipid analyses and samples for storage in a biobank for future research will be collected. Furthermore, FH cases and controls will be invited to have a transthoracic echocardiography and a cardiac CT performed.Ethics and disseminationThe project has been approved by the Ethical Committee and the Data Protection Agency of the Faroe Islands. The project is expected to provide important information, which will be published in international peer-reviewed journals.