Identifying atrial fibrillation (AF) as the cause of stroke is important because it may trigger a change from therapy with antiplatelet agents to proven superior therapy with anticoagulants. Ischemic stroke due to chronic AF is readily diagnosed, but if patients with intermittent AF remain in sinus rhythm throughout their hospitalization, they will likely be discharged on inferior treatment. Numerous monitoring techniques can identify intermittent AF, and the available evidence suggests that prolonging the duration of monitoring increases the likelihood of detecting AF, which supports the use of monitoring beyond the currently recommended 24 h. Further research is required to definitively establish the utility of cardiac monitoring and identify the optimum method and duration. The promise of new drugs to replace warfarin in the near future reinforces the importance of this line of research. Even using current therapeutics, optimizing the diagnosis of AF remains a key component of quality care for patients with ischemic stroke.