Acquired hemophilia A (AHA) is a rare antibody-mediated condition in which autoantibodies form against a coagulation factor, most commonly factor VIII (FVIII), causing severe coagulopathy. Here the present report presents a case of AHA in a 35-year-old postpartum woman with continuous polyserous bloody effusions who was admitted to the First Affiliated Hospital of Zhejiang Chinese Medical University (Hangzhou, China) in October 2017 without a history of trauma, anticoagulation treatment or coagulopathy. At presentation, the patient's hemoglobin level was low (70 g/l; normal range: 115-150 g/l) g/l, blood pressure was 89/58 mmHg (normal range, 90-140/60-90 mmHg), and activated partial thromboplastin time was 68.4 sec (normal range: 25.0-36.0 sec), with a normal international normalized ratio (0.94; normal range, 0.8-1.2). The reaction time in thrombography was prolonged (35.8 min; normal range: 5-10 min), coagulation FVIII had markedly decreased activity (12.6%; normal range, 60-150%), and FVIII inhibitor had a high titer [7.4 Bethesda units (BU)/ml; normal range, 0-0.6 BU/ml]. Notably, the patient's autoantibody level was markedly higher than normal (1:320; normal range: <1:100). The patient was successfully treated with bleeding control, eradication of FVIII inhibitor, and treatment of the underlying disease. To the best of our knowledge, this is the first case of AHA with polyserous bloody effusions in a patient with an autoimmune disorder during the postpartum period. Reports of such rare cases will aid the characterization of disease pathogenesis, which may in turn lead to the recognition and timely treatment of this rare disorder.