23 descendents of a 74--year-old Englishman who had beta-thalassaemia trait, and died of hepatoma, were studied to discover whether thalassaemia minor alone could predispose to iron overload. Serum ferritin and HLA antigens were assessed in all members, and adults underwent radioiron investigations and liver biopsy. 2 members of the second generation and 1 of the third generation, all of whom had thalassaemia trait, had elevated liver iron concentration, indicating preclinical iron overload. This was not associated with any HLA type. None of the subjects had been treated with exogenous iron. The one member of the second generation who had thalassaemia minor but not iron overload was female, and the 5 members of the third generation with the trait, but with normal serum ferritin levels, were all under the age of 15 years. Members of the family without beta-thalassaemia minor had normal iron metabolism. It is possible that the development of iron overload in 4 members of this family was related to the presence of thalassaemia minor, and not to the inheritance of another abnormal gene causing idiopathic haemochromatosis.