AbstractOpportunistic infections of the external auditory canal or the middle ear due to Pseudomonas aeruginosa occurring in patients with low resistance to infection have a 35 percent mortality rate. Once the process extends into the pneumatized temporal bone, eradication becomes more difficult and the mortality rate increases to 72 percent because of the high incidence of involvement of cranial nerves, adjacent intracranial vessels, and meningitis. Treatment is directed towards the underlying condition, administration of systemic carbenicillin and gentamicin, topical colistin therapy, and judicious surgical debridement. Pseudomonas vaccine may be of help.Fifteen cases are presented. Nine follow the pattern of malignant external otitis and six began as a primary acute otitis media