RESUMEN
Hemoglobin O Arab is a rare abnormal hemoglobin. We report the Clinical and biological features of this disease 20 patients: 16 were compound heterozygous Hb O Arab/Beta thalassemia and 4 homozygous Hemoglobin O Arab. Patients are 7 men and 13 women. Most of them are originated from the North West of Tunisia with a age average of 39. 7 years. Diagnosis was carried out at a relatively old age [26. 9 years old]. The homozygous form was not very symptomatic. The compound heterozygous form was more severe and characterized by a mild form of thalassemia with a moderate microcytic hypochromic anaemia [Hb =8. 8 g/dl]. It was often complicated of thrombopenia due to hypersplenism in 40% of the cases. Treatment was based on occasionally transfusion and splenectomy on event of hypersplenism. Evolution of this disease was generally good with a long lifespan of patients. Haemoglobin O Arab is an abnormal hemoglobin well tolerated except for heterozygous category which requires iterative transfusions. Spelenectomy is indicated in case of hypersplenism. The evolution is generally good with a long survival