We have identified 11 individuals with Wilson's disease, members of five sibships within a larger family which was traced through seven generations. Of 206 other family members evaluated for Wilson's disease, none had abnormally low serum ceruloplasmin or copper levels and none had Wilson's disease. There were two documented instances of consanguinity, associated with two of the five affected sibships and four of the 11 affected individuals. The patterns of occurrence of Wilson's disease within the family is consistent with the hypothesis that the disorder is transmitted as an autosomal recessive characteristic. It is likely that the apparently high frequency of disease within the family can be explained solely by the founder effect.