Congenital afibrinogenemia is a rare co­ agulation disorder with an autosomal reces­ sive inheritance. Its prognosis has recently been improved through the administration of human fibrinogen. But fibrinogen adminis­ tration rarely induces severely hypersensitive reactions, and death due to anaphylaxis has been reported in some cases 1 ,2 • This is a report on a patient with congenital afib­ rinogenemia with a history of hypersensitive reactions (bronchospasm, hypotension and skin rash) after administration of fibrinogen. The successful treatment of the case with human fibrinogen and fresh frozen plasma, after rapid desensitization to prevent hyper­ sensitive reactions, is described.