Background Atrial fibrillation is a major risk factor for ischaemic stroke. We investigated whether active screening for atrial fibrillation in secondary care, followed by careful evaluation of risk factors and communication to general practitioners from stroke specialists, could increase appropriate anticoagulation prescription. Methods Between 1/9/14 and 28/2/15 all acute medical admissions were screened for atrial fibrillation at Cambridge University Hospital. Individualised letters were sent to the general practitioners of patients who it was felt would benefit from anticoagulation. Results In total, 847 patients with atrial fibrillation (15% prevalence, 52% female, median age 81.9 years, median CHA2DS2-VASc 4.4) were identified; 671 (79.2%) had known atrial fibrillation, and 176 (20.8%) were diagnosed on admission. After screening and identifying 'at risk' patients, 112 individualised letters were sent to GPs. A 91% response rate was achieved, resulting in an additional 43 individuals being appropriately anticoagulated. Conclusions Atrial fibrillation prevalence is significantly increasing among acute hospital admissions; these patients have high risk of cardioembolic stroke. Careful screening and identification in secondary care can lead to improved rates of anticoagulation.