Aim The aims of this study were to estimate the frequency of hearing loss in children with cerebral palsy (CP), to examine factors associated with hearing loss, and to describe aspects of hearing in a population sample of children with CP and hearing loss. Method A systematic review of the international literature was undertaken, and data on the frequency of hearing loss or severe hearing loss were extracted from 14 data sets based on previously devised criteria. Six hundred and eight-five children with CP (406 males, 279 females) born in Victoria, Australia, between 1999 and 2004 were identified from the Victorian Cerebral Palsy Register. Children were included if they had an established post neonatal cause for their CP before the age of 2years. Additional information was collected on 48 children with documented hearing loss based on a four-tone pure tone average in the better ear. Results There was considerable variation in the definitions and proportions of hearing loss (range 4-13%) and severe hearing loss (range 2-12%) reported by CP registries in developed countries. In Victoria, 7% of individuals with CP had bilateral hearing loss of a moderate to profound degree, whereas the subgroup with a severe-profound degree of loss constituted 3% to 4% of the CP population. Interpretation These population-based data are likely to more accurately reflect the true frequency of defined hearing loss in children with CP than previous reviews.