A case of shared-induced paranoid (psychotic) disorder (DSM III-R, 1987) between mother and son is presented. This disorder may be a more frequently occurring disorder than is generally recognised. It is suggested that more detailed family and social investigations be undertaken to unearth psychopathology in the social environment of the patient. In cases involving relatives, this may be another dimension to the genetic influence on mental illness. This is the first case reported in the West Indian medical literature.