Summary.The iron status of 31 patients with sickle cell anaemia (Hb SS) and balanced globin chain synthesis was studied. Twelve patients (group I) had never been transfused; 14 had received up to 4 units of blood in the past (group II) and five had been hypertransfused for 6 months to 2 years (group III). The hypertransfused group had significantly higher MCV and MCH than the nontransfused one, and significantly lower total iron binding capacity and higher serum ferritin concentration than either groups I or II. The serum ferritin concentration was lower than normal in eight patients (five in group I and three in group II), and higher than normal in seven patients (four in group III and three in group II). The remaining 16 patients had normal serum ferritin concentrations. Our results indicate that iron overload is uncommon in adults with Hb SS who have not been transfused, and that a proportion of patients have lower than normal serum ferritin concentrations. Transfused patients, even 6 months after the last transfusion, show increased haemoglobin content of red cells, which may have an adverse effect on the frequency and severity of sickle crises.