BACKGROUND: Although current guidelines do not recommend immediate anticoagulation therapy (IAC) for acute ischemic stroke, judicious debates are still lingering on whether it might be done for acute cardioembolic stroke (ACES). We surveyed current practice patterns of anticoagulation therapy for ACES in Korea, and analyzed their related factors. METHODS: Using a web-based system, all neurology staffs of training hospitals in Korea surveyed about when and how they commenced anticoagulation therapy in the hypothetical cases with ACES. RESULTS: Of the 359 subjects invited, 281 responded to the e-mail, of whom 76 abstained from participating. The number of participants was therefore 205 (57.1%). Although a few physicians (4.4%) always performed IAC and some (10.7%) never did, most physicians made different decisions according to infarct size and presence of hemorrhagic transformation (HTr): IAC was performed more often in cases with medium-sized or small infarct than large one (68.2% vs. 35.9%, P<0.001), and in cases without HTr (68.6% vs. 34.9%, P<0.001). The most common method of administration was 'heparin followed by warfarin' (68.2%), and then 'warfarin alone' or 'warfarin with aspirin'. If IAC was not commenced, it resumed most commonly between 1 and 2 weeks after the onset (44.0%). CONCLUSION: Quite many neurologists in Korea did IAC in selective ACES, e.g. small sized infarction without HTr. Further studies are needed to prove the efficacy of IAC therapy in this selective population.