An epidemiological and a clinical study were conducted to examine the importance of pregnancy and delivery complications in the genesis of cerebral dysfunction, the studies comprising a total of 495 children of 8 years of age. In the case definition of cerebral dysfunction, methodic improvements were used that had been demanded by those who had been critical of the clinical procedure. The results showed that clinical dysfunction is a risk factor for diseases in child psychiatry. There were no signs pointing to uniform psychopathological patterns (on the lines of a hyperkinetic syndrome) in children with cerebral dysfunction. There was no enhanced incidence of other diseases in the anamnesis of children with cerebral dysfunction. On the whole, the concept of cerebral dysfunction cannot be upheld at least to the extent presumed so far. A comparison between field study random samples and clinical study random samples showed that the classical postulates of the concept apply at most to a negligible minority only.