Acquired hemophilia A is a rare disease. The incidence has been estimated to be 1.3-1.5 cases per 1 million persons per year. The etiology of acquired hemophilia A varies. It may develop in patients with autoimmune disorders, hematologic and solid cancers or in women during pregnancy or following childbirth. In about half of the cases no underlying disease can be found. The clinical picture is dominated by severe soft tissue hematomas especially in the cases of pregnancy-related acquired hemophilia A. Unlike congenital hemophilia A, bleeding into joints is rare. Pregnancy-related acquired hemophilia A may develop following any pregnancy but is observed more often in primigravidas. In most cases it arises in the postpartum period, most commonly 1-4 months after delivery. If factor VIII inhibitors develop during pregnancy or labor, they are frequently associated with severe uterine bleeding. The prognosis of pregnancy-related acquired hemophilia A is good with a high percentage of spontaneous remissions especially if the inhibitor was detected postpartum. Patients with acquired inhibitors do not usually have personal or family history of bleeding tendency, thus it is the presence of bleeding at multiple sites with prolonged activated partial thromboplastin time not corrected by incubation with normal plasma (mixing study) that raises the suspicion of inhibitor. Prompt diagnosis and treatment achieved by close collaboration among gynecologists and hematologists may improve the prognosis and prevent severe bleeding.