From May, 1978 to October, 1983, 88 children with otitis due to Pseudomonas aeruginosa were seen at Paediatric Unit E.N.T. consultation of the University Hospital of Tours. Epidemiologically, it is worth mentioning that the majority of these infections was not of nosocomial origin: 56 children were infected outside the hospital and 26 during their stay in hospital; 3 neonates were referred directly from the Maternity Unit. Most strains of Ps. aeruginosa, with various serotypes, were sensitive to azlocillin. Twenty-four children received a systemic treatment required by their local or general condition. Azlocillin was used in 24 cases on the basis of positive sensitivity tests and was occasionally combined with topical treatment using antiseptics or the antibiotic itself. Or the 3 failures observed, 2 were due to acquired resistance to azlocillin and 1 to chronic otitis. An incomplete result was obtained in a case of otitis externa caused by a strain of intermediate sensitivity. The remaining 19 cases were cured, including 3 neonates with otitis externa or media, 1 child with otitis externa, 1 with combined otitis externa and media, 10 with otitis media, usually protracted, 2 with mastoiditis medically cured and 1 with superinfection following mastoidectomy for cholesteatoma. Secretions dried up within 3 to 4 days and treatment was discontinued after clinical cure was obtained in 9 to 19 days. Fever, which was present in 7 cases, abated within 2 to 8 days. The only relapse that occurred, one month after treatment of an otitis media, responded to a second course of azlocillin.