Twenty five patients with lesions of the Fallopian canal were assessed: in 13 the canal was destroyed, in 7 the nerve sheath was involved and in 5 the nerve fibres were involved. Electrical and clinical testing was normal of patients with minor involvement of the nerve fibres. In poorly pneumatized mastoids the probability of osteitis close to the facial nerve must be remembered because of the dangers of latent localized mastoiditis. In all patients with chronic otitis media with granulations, cholesteatoma and osteitis the Fallopian canal should be metriculously explored surgically, and when found involved in disease it is recommended that the nerve be examined and that a "small decompression" of bone without slitting the sheath be performed.