Dysfibrinogenaemia is an inherited disorder, characterised by a plasmafibrinogen in normal concentration, but of abnormal quality due to impaired release of fibrinopeptides and/or impaired aggregation of fibrinomonomers. The typical abnormalities of the laboratory findings will be demonstrated by presenting the case reports of 4 patients with 5 pregnancies (1 ectopic pregnancy); the importance of clinical exploration is emphasized. Newborn infants must be subjected to careful clinical and biochemical examination, because of factors of Mendelian dominant inheritance.