Atrial fibrillation (AF) is the most common arrhythmia, with more than 100 000 confirmed cases in Norway. A feared complication of AF is ischemic stroke. About 15% of ischemic strokes can be directly linked to clinical AF, while over 25% are cryptogenic and without any known cause. AF can present with typical symptoms, but several recent studies have shown that up to 40% of patients have no symptoms at all, and that a part of the cryptogenic strokes may be caused by an asymptomatic and unknown AF. There are no studies concluding that asymptomatic AF has better outcomes than symptomatic, and ischemic stroke may be a feared and acute presenting symptom of the AF in this group. Use of oral anticoagulants reduces the risk of stroke with 64-70 %, but undertreatment is a clinical problem, knowing that AF often is asymptomatic and underdiagnosed. Considering the high prevalence of AF, the great portion of people at an asymptomatic stage, that we have a well-documented treatment for clinical AF and different options for diagnostics, it should be discussed if AF is a potential candidate for systematic screening in Norway in order to reduce the number of ischemic strokes.