Background: Patient’s knowledge of anticoagulation therapy is important to achieving and maintaining optimal therapy outcome as well as reducing adverse events. The aim of this study was to assess knowledge of warfarin therapy among patients attending Warfarin Clinic at a public hospital. Materials and Method: A cross‑sectional survey of 128 patients was conducted at a Warfarin Clinic. Face to face interviews were conducted, using standard questionnaires to determine demographic characteristics and knowledge of warfarin therapy. Results: The mean age of participants was 50.5 years. Majority of patients were male (56.2%), Malays (46.89%) and married (78.1%). A large proportion of patients had only primary (33.6%) and secondary school education (43.0%). The result indicates almost all patients know the indication (95.8%) and dosage (92.2%) of warfarin. In addition, 89.1% of patients know what to do in case of a missed dose. However, more than half of participants do not know the consequence of missing a dose. Most patients know the purpose of INR monitoring and the consequence of INR value above or below the therapeutic range. There were only 42.2% of the patients who know the frequency of INR monitoring. Knowledge of drug interaction indicates more than 50% of patients possess knowledge of warfarin‑alcohol, warfarin‑vitamin, warfarin‑OTC and warfarin‑food interaction. There were 64.1% of patients who know when to seek immediate medical attention and 56.3% who are aware of side effect monitoring. Categorization of knowledge level shows 41.4% of patients have good level of knowledge about anticoagulation therapy. However, only 33.6% of patients have excellent knowledge while 1.6% of patients were found to have poor knowledge of warfarin therapy. Conclusion: It can be concluded majority of patients attending warfarin clinic have insufficient knowledge about warfarin therapy.