Small portable devices that generate a prothrombin time/INR from fingerstick capillary blood simplify warfarin management by allowing selected patients to monitor and manage their own warfarin dose. Early studies established that patients can self-test at home, with results as accurate as those obtained by practitioners. Point-of-care testing of elderly patients resulted in tighter INR control and a lower incidence of major hemorrhage, especially at the initiation of anticoagulant therapy. Patients can also successfully self-manage warfarin therapy. Larger, prospective, randomized intervention studies have shown that patient self-management led to greater time spent within the therapeutic INR range. However, a shift toward patient self-testing will likely require centralized implementation of patient education, training, and follow up that will need to be established in the clinic setting or by a third party.