Patients taking warfarin frequently present with excessively elevated, but otherwise asymptomatic, INR values. Management of such patients is controversial, as treatment must weigh the risks of hemorrhage and thrombosis. To determine current practice patterns in the management of warfarin-induced excessive anticoagulation (AC), specifically with respect to vitamin K usage, we performed a physician survey. We gathered information on practice habits, and assessed compliance of those habits with the 1998 American College of Chest Physicians (ACCP) guidelines for the reversal of excessive AC. In this evaluation, members of the Canadian Society of General Medicine, residing in Ontario, were asked to provide management preferences in 6 clinical scenarios involving patients taking warfarin who present with a high INR value. The scenarios contained various combinations of INR value, treatment setting, and the presence and severity of bleeding. A total of 201 surveys were sent, and 117 responses received. Fifteen surveys were excluded, leaving 102 analyzable. We found that in scenarios with INR values of < 5.2 without bleeding, conservative approaches, complying with the ACCP guidelines, were chosen by 89 to 99% of respondents. In scenarios with INR values of > 7.1 and/ or bleeding, use of vitamin K (in any form) was between 71 and 82%. However, compliance with ACCP guidelines was between 1 and 62%, because respondents selected inappropriate vitamin K doses, or routes of administration. In 5 of the 6, scenarios the most common route of vitamin K administration was subcutaneous, which is not recommended by the ACCP. We conclude that in this physician sample compliance rates with the 1998 ACCP guidelines were variable, and were lowest in scenarios describing patients who required the most urgent reversal of anticoagulation. These findings highlight the need for further methodologically valid investigations in this area.