Use of drops in the external ear canal for relief of pain, myringotomy, or even in the treatment of nonperforating otitis media is based mainly on empiricism. Investigation of the value of such therapy is indicated. The solution of these problems resolves itself into proving whether there is permeability of the tympanic membrane. The purpose of this study, is to discuss factors governing permeability in general, with the specific objective of scrutinizing topical anesthetics used on the eardrum. A review of the literature1,2 attests to these important facts: First, local anesthetics for all practical purposes can be considered as not being absorbed from intact skin (which does form part of the eardrum)3,4; second, very little has been proved about permeability of membrane,5 and, third, papers in medical journals on anesthesia of the eardrum are rare. Comparative Thickness of Eardrum and Permeable Membranes Most permeability studies5 have