A new autosomally inherited dysfibrinogenaemia was recognized in 3 members of an Italian family. No bleeding tendency or thrombotic disease in any of the affected members were demonstrated. Coagulation tests revealed prolonged prothrombin, thrombin and Reptilase times. Plasma fibrinogen levels were normal with immunologic method and slightly reduced with chronometric assay: the other blood coagulation factors were normal. In addition, cross-immunoelectrophoresis performed on patients' plasma was indistinguishable from the normal. Dysfibrinogenaemia was confirmed by studying the purified fibrinogen. The fibrin polymerization curve, measured spectrophotometrically, showed a lower slope than the normal. A delay in fibrin monomer aggregation was revealed when compared to the normal at an equal concentration. The release of fibrinopeptides was normal. SDS polyacrylamide gel electrophoresis, isoelectric focusing and cross-immunoelectrophoresis of purified fibrinogen were not able to demonstrate any structural abnormality. The fibrinogen was named fibrinogen Genova.