Acquired hemophilia is a rare but severe condition, which is unknown to medical specialties outside hematology. Sudden appearance of antibodies against coagulation FVIII is diagnosed by abnormal subcutaneous large and multiple hematomas with minor injuries only. APTT is prolonged, FVIII activity variably low and inhibitor titer varies, too. The antibodies are typically occurring in women after delivery and later in life at around 60 years of life due to immunological challenges, and in association with malignant diseases. Rapid recognition of the condition and support of hemostasis together with immunosuppressive therapy is important, since the diagnostic delay is a poor prognostic sign. Coagulation experts should be consulted to arrange the management and followup of the patients. Management of bleeds consists of so-called FVIII bypassing agents, activated prothrombin complex concentrate, aPCC, recombinant FVIIa or porcine FVIII. The immunotherapy should be continued for several weeks according to the timing of the remission. The relapse rate needs to be noted in the future under similar situations as the index event occurred. Register data collection is important to characterize this lifethreatening acquired bleeding disorder.