The study was undertaken to define the characteristics of spontaneous eardrum perforation in acute otitis media. Eighty (29.5 per cent) out of 271 children with acute otitis media had eardrums which perforated. An increased incidence of perforation was associated with a previous history of otitis media. All perforations were small and limited exclusively to the pars tensa. In 85 per cent of the patients, the perforation was located in the anterior-inferior quadrant. It had smooth margins enabling free drainage of pus and was associated with a favourable clinical course. In the remaining 15 per cent of the cases, the perforation was located in the posterior-superior quandrant. It had a nipple-like shape with a tiny opening that did not allow pus to drain sufficiently from the middle ear. The perforation closed in 94 per cent of the patients within one month. The healing process was gradual and following perforation closure, there was evidence of middle ear effusion for some time before normal aeration was regained.