Alemtuzumab (ALZ) is an anti-CD52 monoclonal antibody used to treat recurrent remittent multiple sclerosis (RRMS). After ALZ infusion, there is a depletion of T and B cells expressing CD52, while the stem cells and innate immune cells are spared. Longitudinal studies with long periods of follow-ups have reported ALZ-associated autoimmune diseases, such as thrombocytopenic purpura and thyroiditis. We report two patients who developed autoimmune hemophilia A or acquired hemophilia (AHA) after ALZ infusion, one of whom developed severe vitiligo. To the best of our knowledge, these two cases of ALZ-associated AHA are the first two cases to be reported in Brazil, and the fourth and fifth AHA cases to be reported worldwide. AHA is a potential life-threatening disease if not diagnosed and treated in a timely manner. The development of AHA should be cited as a possible adverse event, and specific coagulation tests must be part of the official recommendations for patient follow-ups.