Antibiotherapy has lead to a substantial decrease in the number of infants with acute mastoiditis or complications thereof. However, the non-negligible incidence of protracted otitis currently observed has caused one to raise several pathogenid hypotheses, among which subacute mastoiditis figures as one needing to be detected early. This prospective study was conducted on 118 children treated for protracted otitis in the ENT Service at Hopital Trousseau, during the period from january 1987 to december 1988. It allowed us to develop diagnostic and therapeutic strategies to cope with the difficult problem of protracted otitis, taking into account bacteriologic findings and risk factors, among other things.