Summary Atrial fibrillation (AF) is associated with a significantly increased stroke risk which is highly preventable with appropriate oral anticoagulant therapy (OAC). However, AF may be asymptomatic and unrecognised prior to stroke. We aimed to determine if single time-point screening for AF could identify sufficient numbers with previously undiagnosed AF, to be effective for stroke prevention. This is a systematic review of clinical trials, by searching electronic medical databases, reference lists and grey literature. Studies were included if they evaluated a general ambulant adult population, using electrocardiography or pulse palpation to identify AF. We identified 30 individual studies (n=122,571, mean age 64 years, 54% male) in nine countries. Participants were recruited either from general practitioner and outpatient clinics (12 studies) or population screening/community advertisements (18 studies). Prevalence of AF across all studies was 2.3% (95% CI, 2.2–2.4%), increasing to 4.4% (CI, 4.1–4.6%) in those ≥65 years (16 studies, n= 27,884). Overall incidence of previously unknown AF (14 studies, n=67,772) was 1.0% (CI, 0.89–1.04%), increasing to 1.4% (CI, 1.2–1.6%) in those ≥65 years (8 studies, n= 18,189) in whom screening setting did not influence incidence identified. Of those with previously unknown AF, 67% were at high risk of stroke. Screening can identify 1.4% of the population ≥65 years with previously undiagnosed AF. Many of those identified would be eligible for, and benefit from OAC to prevent stroke. Given this incidence, community AF screening strategies in at risk older age groups could potentially reduce the overall health burden associated with AF.