Patients with sickle cell disease (SCD) may develop functional asplenia as a chronic complication, secondary to repeated episodes of polymerisation of haemoglobin S. It is known that increased plasma concentrations of fetal haemoglobin (HbF) reduce the polymerisation of haemoglobin S. Hydroxyurea is a chemotherapeutic agent capable of increasing HbF levels in the red blood cells and its use has recently been proposed in the treatment of SCD. The objective of this study was to evaluate the effects of long-term therapy with hydroxyurea on recovery of splenic function. Twenty-one patients (aged 3-22 years; 14 with SS haemoglobinopathy, 7 with Sbeta(0) haemoglobinopathy) were studied with liver/spleen scintigraphy before and after 6 and 12 months of treatment. All studies were submitted to visual inspection and semi-quantitative analyses using spleen/liver ratios. Imaging prior to treatment demonstrated functional asplenia in nine SS patients and one Sbeta(0) patient and impaired splenic function in five SS patients and six Sbeta(0) patients. After treatment, splenic function improved in ten patients, remained unchanged in eight and worsened in three. Using liver/spleen imaging, it was possible to demonstrate that hydroxyurea is capable of improving splenic function in some SCD patients. Improvement is not always possible and frequently does not lead to a normal splenic function even after 1 year of treatment.