In this review of cochlear malformations, 17 cases were studied by CT scan (high resolution-target program) including 10 males and 7 females. The anomaly was bilateral in 12 cases and unilateral in 7 (the latter included 2 Mondini type aplasias and one Michel). The cochlear malformation (whose most frequent expression was the cochlear hypoplasia with 1 or 1 1/2 spires-65% of the cases) was associated to semicircular canals and/or vestibular aqueduct anomaly in 82% of the patients; it was exclusively of the anterior labyrinth in 18% of the cases. A middle ear malformation coexisted in 29%: in 3 cases with malleoincudal dysmorphy only and with tympanic aplasia in 2 others. These cochlear anomalies with CT expression were discussed considering the embryology, in view of a possible gestational dating, moreover relating to the hipocusia type: perceptive or combined.