- This study attempted to produce a simple, scorable test of neurological function and to see whether, in the absence of obvious central nervous system disease, the neurological impairments so defined were related to psychiatric disorders. 138 children aged between seven and 11 years from four schools undertook a standardised test based on the Fogs' test. Those who performed poorly on the test had a higher frequency of behaviour problems, motor inco-ordination and adverse perinatal events. Children with any kind of behaviour problem had more difficulty with the test than those without, but hyperactive children did worse than antisocial children. The strength of the statistical association between behaviour problems and functional neurological impairment varied with the social circumstances of the children. Neurological impairment was found more frequently among behaviour-problem children from suburban schools than those from inner-city schools. It appears that a degree of dysfunction lying between brain damage and normal variation places children at higher risk for the development of behaviour problems. Such dysfunction, together with psychosocial disadvantage, may be important aetiological factors in behaviour disorders during childhood.