Schizophrenia is a disabling psychotic disorder characterized by hallucinations, delusions, and impaired functioning in many aspects of everyday life. The established condition generally becomes manifest in early adulthood, and evidence suggests that one of the most important risk factors for developing the disorder is inherited vulnerability. The established illness has been shown to be associated with deficits in many domains of cognitive function, along with structural and functional brain abnormalities, most notably in pre-frontal and temporal lobes. However, such studies have not been able to determine the extent to which such deficits relate to the presence of a schizophrenic predisposition, the presence of symptoms, and/or medication effects. A number of research groups have therefore turned to the study of relatives of affected individuals with the aim of determining if similar cognitive deficits and brain abnormalities are also found in those with increased genetic vulnerability to the disorder. In this article, studies on such individuals are discussed. It is concluded that deficits are apparent in relatives that are similar to but less marked than those seen in patients with schizophrenia.