The folic acid plasma level in 12 out of 13 children with thalassemia major was lower than 3 ng/ml. This deficiency is not due to intestinal malabsorption. Folate deficiency should then be provoked by an increased allowance due to the compensatory erythropoiesis and to the lack of. Folic acid level less then 3 ng/ml in 24% and not more then 6 ng/ml in 50% of thalassemic heterozygotic children has been found. Therefore the necessity of folic acid treatment in thalassemic children with a low blood transfusional therapy and in beta-thalassemic heterozygotic children has been recommended.