To obtain the best possible results of treatment of acquired cholesteatoma, we made a subdivision of cholesteatoma types into attic and pars tensa cholesteatomas, and subdivided the latter further into tensa retraction cholesteatoma and sinus cholesteatomas. Tensa retraction cholesteatoma is defined as arising from a retraction or perforation of the whole pars tensa, whereas sinus cholesteatoma is defined as arising from a retraction or perforation of the postero-superior part of the tensa. We present the long-term results obtained in tensa retraction cholesteatomas treated with one stage surgery from 1964 to 1980. Median observation time was 9 years, range 2 to 19 years. Sixty-one ears were treated without mastoidectomy, whereas 71 ears had canal wall-up mastoidectomy and 64 ears had canal wall-down mastoidectomy. The total recurrence rate was 13.3 per cent; 17 ears had residual cholesteatoma, and nine ears had recurrent cholesteatoma. The best results were obtained in ears with an intact ossicular chain where mastoidectomy was not performed. In 49 per cent of the cases, the cholesteatoma was confined to the tympanic cavity without reaching the aditus, antrum or mastoid process. About one-third to one-quarter of the ears had tympanoplasty only, with removal of the cholesteatoma through the ear canal.