Warfarin (Coumadin) continues to remain the mainstay of oral anticoagulant therapy (OACT) for thromboprophylaxis for both venous thromboembolic disease (VTD) and cardiac indications. However it needs careful monitoring because of its narrow window of target activity level, interaction with numerous medications and food items, caution for use in patients with co-morbidities like hepatic and renal impairment and bleeding lesions and the risk of major hemorrhage. A large part of its success and safety requires the patients own understanding and participation in its control. In a retrospective study on 153 patients on long term OACT with warfarin, we have analyzed the influence of various personal characteristics of the local patient population like age, gender, nationality, education and financial status, family size, family style, manner of drug administration and number of other medications prescribed for co-morbidities. Ability to achieve consistently efficacious target level of anti coagulant activity is adversely affected by older age, female gender, lower education status, larger family size, joint family setting, dependence on domestic servants to administer warfarin and larger number of other medications taken for co-morbidities. Thirty-seven patients were identified from such vulnerable personal characteristics and assigned to a separate anticoagulant therapy control clinic with specific arrangements for stricter control. This group of patients was studied prospectively for 18 months. Significant improvement was apparent on comparison of their performance before and after assignment to the separate clinic.