This paper presents the results of a national comparative audit of mastoid surgery, retrospectively analysing 611 operations by 55 consultants. Confidentiality for both patient and surgeon was assured. For cholesteatoma 80% of mastoidectomies performed were open cavity procedures and for other middle ear disease 58% used an intact canal wall technique. Thirty-two surgeons used only an open cavity mastoidectomy for cholesteatoma during the period of the audit. There was a statistically significantly greater number of wet ears with open cavities than with closed cavities, but the frequency of the operator did not correlate with the dry ear rate. Ten serious complications (facial palsy and dead ear) were recorded. All occurred in open cavity mastoidectomies. The post-operative hearing status was unknown in 40% of patients.