Cochlear implants now play a standard role in the management of adults with acquired profound sensorineural deafness. Their role in children is more controversial. However, as demonstrated by a 1979 report on childhood deafness in the European Communities, there is no reason for complacency in the present management of profoundly deaf children. Transtympanic electrocochleography has been used as a method of estimating neural survival in deafened adults being assessed for the U.C.H./R.N.I.D. single channel extracochlear implant and also in a parallel group of profoundly deaf children referred by a paediatric hearing assessment clinic. In adults the effectiveness of electrocochleography in judging neural survival was monitored by electrical stimulation of the cochlea and found to be significantly effective. This result was extrapolated to the paediatric group to estimate the proportion of congenitally deaf children who might benefit from a cochlear implant. It is suggested that in a programme designed to implant such children at 2 years of age, techniques should be chosen that neither damage the cochlea nor the middle ear sound conducting mechanism.