FOR MANY years physicians have been interested in the problem of how to close tympanic perforations, and numerous methods have been employed. The method to be considered here is also an old one, namely that of cauterization of the margins of the perforation with trichloroacetic acid, which was apparently first used by Okuneff in 1895. Justification for this type of treatment seems to lie in the fact that following a perforation of some duration the epithelial outer layer of the tympanic membrane tends to grow over the margin of the perforation toward and sometimes into the middle ear. This leads to the formation of an epithelized hole or communication to the middle ear which then has no chance to close. If the epithelium could be discouraged from growing inward until the fibrous and mucous membrane layers could form a structure or bridge for this migration, one might expect to close