Objective: The study aimed to investigate the use of hydroxyurea (HU) for the treatment of beta-thalassaemia (beta -thal) patients. Methods: We examined the haematological effects of orally administered HU (10-20 mg/kg/d) in 11 patients, including four beta -thal major and seven beta -thal intermedia patients. Complete blood count and levels of foetal haemoglobin (HbF), liver enzymes and serum creatinine were evaluated before and during HU. Response to therapy was evaluated at 6 months of treatment. Results: A substantial increase in haemoglobin (Hb) level (4.1 g/dL), leading to complete withdrawal from a regular transfusion programme, was observed in one unique beta -thal major patient. In the beta -thal intermedia patients, increases in Hb level of 1.3, 1.9 and 2.0 g/dL were observed in three of seven (42.9%) patients during HU therapy. The mean values of Hb, mean corpuscular haemoglobin (MCH), and HbF were higher during HU treatment than baseline values (8.7 vs. 7.7 g/dL, P = 0.05; 26.7 vs. 22.9 pg, P = 0.05; 57.2 vs. 44.9%, P = 0.04; respectively). In contrast, the mean reticulocyte count measured during therapy decreased (97.0 x 10(9) vs. 632.0 x 10(9) /L, P = 0.03). No correlations were observed between levels of Hb and HbF (r = 0.77, P = 0.10), and levels of Hb and reticulocyte counts (r = 0.26, P = 0.31). No significant toxicity was observed in our patients. Conclusion: These results suggest that HU may improve Hb levels in beta -thal. Thus, we may conclude that a large trial concerning the response to HU in these patients should be carried out to clarify this issue.703151155