The sex-ratio in childhood deafness is analyzed and shows an unexplained male predominance. A review of the literature is presented and to this is added the sex-ratio of 3278 ex-pupils from the Dutch Institute for the Deaf in St. Michielsgestel. Also the sex-difference of 162 deaf children is presented and related to the degree of hearing loss and the etiology of their deafness. The population of these hearing impaired and deaf people consists of an average of 54% men and 46% women. Although hereditary etiology was spread equally over both sexes of the 162 pupils in the Nijmegen school, a significant difference for the autosomal dominant forms of hearing impairment have been observed. An explanation for this male predominance is still lacking.