The aim of this study was to establish rates of behavioural and emotional problems, and of social maladjustment, in a population of deaf children, particularly in relation to different methods of communication. The parents of 84 children who attended two schools for the deaf took part. They completed the parents' checklist (PCL), a behaviour rating scale for deaf children, and the Child Behaviour Checklist (CBCL), a measure widely used in the general population. The two instruments were significantly correlated on the severity of behavioural and emotional problems, but their previously established cut-off scores detected different rates of possible clinical cases, i.e. children with mental health disorders. According to the CBCL, 40% of children were within the clinical range, and 82% were socially dysfunctional compared with the general population. The PCL identified a much higher percentage (77%) of caseness. Behavioural and emotional problems were significantly higher in Asian children. Although all subjects used sign language, the additional use of speech, which may indicate increased hearing ability, had a protective effect for adolescents. The findings are discussed in relation to the validation of the instruments and the development of intervention programmes for deaf children.