Conventional behavioral testing of hearing shows that children with Down syndrome have a high prevalence of hearing deficits. However, most young (< 3.5 years of age) children with Down syndrome are unable to cooperate in this type of testing. We evaluated auditory brain-stem responses of 47 unselected patients 2 months to 3 1/2 years of age. Thirty-four percent had normal hearing, 28% had unilateral loss, and 38% had bilateral loss. Type of loss was conductive in 19 ears, mixed in 14, and sensorineural in 16. Degree of loss was mild in 33 ears, moderate in 13, and severe to profound in 3. Language quotients and degree of hearing loss were compared and an association was not found. Because of the high prevalence of hearing loss in children with Down syndrome, we recommend evaluation of auditory brain-stem responses in the first 6 months of life.