Three young unrelated propositi had β-thalassaemia trait (β-th-t) and chronic unconjugated hyperbilirubinaemia (UH). Red blood cell 51Cr t/2 was slightly reduced (from 19.0 to 22.8 days), liver function and histology, and iron metabolism included ferrokinetics and iron-chelation with Desferrioxamine B were normal. Bone marrow smears did not show features of dyserythropoiesis. Out of 20 relatives with normal liver function, β-th-t was present in 7, UH in 7, and β-th-t and UH in 3, while the remaining 3 subjects were normal. UH was chronic, benign, familial, without overt signs of haemolysis and with normal liver function, (and histology in 3 propositi); it was therefore of Gilbert’s type. Bromsulphophthalein kinetics and the reduced caloric intake test confirmed the diagnosis.