OBJECTIVE To find the rate of therapeutic control and the frequency of complications among patients receiving oral anticoagulant therapy, attending in a primary care center. METHODS Descriptive study over the last four years. METHODS An urban primary care center. METHODS We included all patients in oral anticoagulant treatment controlled in our center among 1989 and 1993, excluding that patients with less than three months in control, or discontinued control. The prothrombin time was measured by international normalized ratio (INR). To measure the therapeutic quality control, we used the method proposed by the International Society of Thrombosis and Haemostasis. The frequency of complications was measured in number of events/100 patients/year. RESULTS In the 136 patients studied the average time in control was 23.57 months. The 68.37 percent of determinations were within satisfactory ranges. The frequency of minor hemorrhages was 13.36 by 100 patients/year, 1.08 of major hemorrhages, and 2.53 of thromboembolism events. CONCLUSIONS The results obtained in this audit are similar to the communicated by other centers. The therapeutic control of oral anticoagulants can carry out in primary care with enough quality and some advantages: more facility to health education, better accessibility, and more integration of anticoagulation therapy in global care of patients.