Bleeding complications are one of the major risks during oral anticoagulation. If further anticoagulation is indicated, low-molecular-weight heparin (LMWH) may offer an alternative treatment in those patients. In a prospective, nonrandomized study, 120 patients have been switched from oral anticoagulants to LMWH because of bleeding complications or other severe side effects during treatment with vitamin K antagonists. Indication for further anticoagulation was prophylaxis of recurrent thromboembolism, artificial heart valve replacement, atrial fibrillation with embolism and cardiomyopathy. The treatment period ranged from 2 months to 10.8 years. No fatal embolism occurred. One major but not severe episode of gastrointestinal bleeding occurred in a patient with an as yet unknown colon carcinoma. The cumulative treatment period amounts to 250 years. No drop in platelet count occurred in any patient. No other side effects were observed. LMWH was injected subcutaneously at doses ranging from 2500 to 15,000 anti-factor Xa units per day by the patient himself. The dose was adjusted on the basis of body weight, bleeding risk and thromboembolic risk. The results indicate that LMWH may be effectively and safely used as alternative anticoagulant regimen in patients with side effects or other complications on oral anticoagulants.