Patients with severe bleeding complications and other side effects on conventional anticoagulants and strong indication for further anticoagulation were treated with a low molecular weight heparin fragment (Tedelparin). In this paper we report the experiences in 30 patients, who were anticoagulated 1-11 months with this compound. All patients injected themselves a dose ranging from 1 X 2,500 to 1 X 20,000 anti factor Xa units per day. Within 132 months of treatment one patient with good compliance developed thromboembolism. Four patients had bad compliance. Two of them experienced rethrombosis 1 and 8 weeks after starting therapy. Severe haemorrhages did not occur. Two patients had one minor bleeding complication each. Both patients developed several times per year severe haemorrhages with conventional anticoagulants. All excessive subcutaneous haematomas and indurations of the adipose tissue at the injection site of conventional heparin disappeared completely. Low molecular weight heparin can be regarded as an alternative anticoagulant in patients with severe bleeding and other complications on oral anticoagulants and conventional heparin.