Acquired hemophilia B is a rare bleeding disorder in which circulating specific antibodies inhibit the coagulation factors. Usually, it is associated with autoimmune diseases, malignancy and some infections such as hepatitis B (HBV) and C (HCV) viruses. The association with the human immunodeficiency virus (HIV) is rare. We present the first case of hemophilia B acquired in a patient with HIV. A 36-year-old woman with a history of HIV infection stage 3 acquired immunodeficiency syndrome (AIDS) (CDC 2014) and glomerulopathy secondary to HIV. She consulted for subacute non-dysenteric diarrhea. During her hospitalization, bacteremia by methicillin-sensitive Staphylococcus aureus ( S.au reus) was documented, requiring hemodialysis catheter replacement with profuse bleeding during the procedure. The coagulation tests showed prolonged activated partial thromboplastin time (aPTT), normal prothrombin time (PT), mixing test with Rosner index: 8.8%, negative lupus anticoagulant, and specific tests for normal factor VIII and XI. The activity of factor IX was <50% and the inhibitor was increased, which confirms the diagnosis of hemophilia B. Acquired hemophilia B in a patient with HIV infection is not a frequent association; it should be suspected in the context of bleeding with prolonged aPTT.