Although tuberculosis is a major problem of public health in Morocco, the tuberculous mastoiditis remains extremely rare, and its diagnosis is often delayed. We report here the case of a 3-year-old child who had unusual chronic left mastoiditis and retro-auricular fistula, associated with spontaneous discharge of bony sequestrum. CT scan of temporal bones showed complete destruction of left mastoid cells. A left mastoidectomy confirmed the tuberculous mastoiditis diagnosis after histopathological examination. The clinical outcome was favorable after anti-tuberculosis treatment. Otologic tuberculosis of the ear is well described in the literature and symptoms include chronic otorrhea with audio-vestibular symptoms. The specificity of this case is that the child had an isolated involvement of the mastoid with spontaneous bony sequestrum discharge, but without otorrhea.