Dysfibrinogenemia is caused by a variety of structural abnormalities in the fibrinogen molecule, which results in a tendency for bleeding and thrombosis as well as obstetric complications. The obstetric complications of dysfibrinogenemia include first-trimester pregnancy loss, hemorrhage, placental abruption, and thrombosis. We conducted a retrospective study of four cases of dysfibrinogenemic patients from one family (fibrinogen Frankfurt III) with a history of recurrent pregnancy loss and who were treated with fibrinogen concentrates. One patient had three consecutive abortions in the 6th, 7th and 11th week of pregnancy. The underlying fibrinogen gene mutation was Aalpha R16C, two propositae being homophenotyic and two heterophenotypic. The median age was 30.5 years (28-39 years). The median level of fibrinogen (Clauss) was 29 mg/dl (range less than 10-51 mg/dl, normal: 150-450 mg/dl), the median level of fibrinogen according to Schulz was in the normal range at 180 mg/dl (range 180-300 mg/dl). The reptilase time was prolonged to 55 s (median, normal: -20 s). Fibrinogen was administered from the beginning of the pregnancy until delivery. In three out of four patients, abortions could be avoided by continuous administration of fibrinogen concentrates commencing as early as possible during the pregnancy in order to achieve fibrinogen plasma concentrations (Clauss) over 100 mg/dl. For the prophylaxis of thrombotic events, low-molecular heparin at a dosage of 40-60 IE/kg was administered postpartum for 14 days.