The emergence of anti-factor VIII and anti-factor IX antibodies in hemophilia A or B is the most serious complication of hemophilia. We aim to expose through a series of patient's data, collected between 02/2009 and 02/2016 in the pediatric service of university hospital of Rabat, Morocco, the epidemiological and clinical characteristics of these patients, and to highlight the therapeutic difficulties encountered during their treatment. Out of 120 hemophiliac patients, we included 22 hemophiliac patients (18.33%, p<0.004) who developed an antibody, 21 patients with hemophilia A. Among the patients, 54.5% (n=12) exhibited moderate hemophilia, while 45.5% (n=10) had major hemophilia. The average age at diagnosis is estimated to 12±6.6 years. The circumstances of diagnosis were dominated by therapeutic inefficiency (63.64% (n=14)), then came dental extraction (9.09% (n=2)), preoperative assessment 22.73% (n=5) and hemophiliac arthropathy in a single case. The titration of antibodies in a 12-person sample ranged from 0.6 UB to 84 UB, of which (41.67% (n=5)) were low responders. The therapeutic treatment was based on fresh frozen plasma (54.55% (n=7)), recombinant activated factor VII (18.2% (n=4)), recombinant activated factor VII and PFC (18.2% (n=4)), and induction of immune tolerance. The occurrence of an inhibitory antibody represents the major residual complication of replacement therapy.