BACKGROUND: Warfarin is highly efficacious for the treatment and prevention of thromboembolic disorders. However, anticoagulation control has been a longstanding challenge, as patients' lack of knowledge of warfarin therapy is a predictor of nonadherence and compromised patient safety. OBJECTIVE: To ascertain whether hospitalized patients newly initiated on warfarin are provided adequate anticoagulation education during hospitalization, as measured at discharge, as well as determine whether there is a difference in the knowledge obtained by patients educated via a structured program versus those counseled by "usual care." METHODS: A prospective evaluation of warfarin education of inpatients new to warfarin therapy was performed at Bassett Medical Center, Cooperstown, NY. Patients who were admitted to the hospital and receiving warfarin for any given diagnosis, were >18 years of age and able to give informed consent, and spoke English were recruited. Patients with dementia or cognitive impairment, those who were pregnant, or those who had previously been on warfarin therapy were excluded. Recruited patients received warfarin education in the form of a structured program provided by a pharmacist or counseling by usual care during hospitalization. Prior to discharge, the Oral Anticoagulation Knowledge (OAK) test, a prevalidated tool used to measure warfarin knowledge, was administered to evaluate outcomes. Further warfarin education was provided posttest if necessary. RESULTS: The intervention group (n = 20) scored significantly higher on the OAK test than the usual care group (n = 20): 74% versus 55%, respectively (p = 0.004). CONCLUSIONS: This preliminary study demonstrated that there is a large amount of variability regarding patient knowledge of warfarin on discharge from an inpatient facility. A formalized inpatient warfarin education program may empower patients to achieve a larger degree of initial warfarin knowledge than those educated by usual care. Previous studies have demonstrated that this may improve adherence and subsequently increase long-term safety associated with oral anticoagulation. Larger, prospective, randomized studies are necessary to further evaluate patient education and safety outcomes.