Congenital afibrinogenemia is a rare disorder with unusual clinical manifestations. The disease is inherited as an autosomal recessive trait and consanguinity is common among affected families. Clinical manifestations range from minimal bleeding to catastrophic hemorrhage. Congenitally afibrinogenemic patients seem to be peculiarly susceptible to spontaneous rupture of the spleen. Coagulation tests which depend on clot formation as an end point may be infinitely prolonged and abnormalities of platelet function are usually present. The diagnosis is established by demonstrating trace or no immunoreactive fibrinogen. The disease is caused by markedly reduced or absent synthesis of fibrinogen by liver cells, but the genetic defect remains unknown. Bleeding episodes can be effectively treated with cryoprecipitate. Purified virally inactivated fibrinogen concentrates have been used in Europe and may soon be widely available.