Severe thromboembolic and hemorrhagic complications following mechanical heart valve replacement essentially occur due to intense oral anticoagulation and fluctuating individual INR values around the target range. INR self-management can help to minimize these fluctuations. Beginning this therapeutic control immediately after mechanical heart valve replacement further reduces anticoagulant-induced complications. Included in the study were 1200 patients. The quality of oral anticoagulation also improved through INR self-management. Over an observation period of two years, nearly 80% of INR values recorded by the patients themselves were within the target therapeutic range of 2.5-4.5. This corresponds to a high significance of p < = 0.001 in favor of INR self-management. Only 64.9% of INR values monitored by family practitioners were within the desired range. The results differed slightly in quality between patient groups with different levels of training (comprehensive, secondary modern, grammar with or without university). Of patients trained in INR self-management following mechanical heart valve replacement, 91.7% maintained their competence in this technique throughout the entire follow-up period. Only 8.3% of those trained immediately after surgery were unable to continue with INR self-management.