Background: Iron deficiency is the most common cause of anemia in the world. It is a major public health concern in preschool children and pregnant women in the developing world. Anemia also reduces physical work capacity and cognitive function and adversely affects learning and scholastic performance in school girls entering adolescence. Aim of work: The aim of this work is to assess the effect of iron deficiency anemia (IDA) on different I.Q parameters as memory, attention, language, and concentration, etc. by using Stanford Benit scale 4. Patients and methods: This prospective case cohort study was carried out at the outpatient clinic, Alazhar University Hospital and Sidi-Galal health insurance clinic at Assiut city from January 2015 to June 2015. The study included 90 children (50 female and 40 male) 60 of them suffering from IDA (40 female and 20 male) in addition to 30 apparently health children of matched age and sex as control group (18 female and 12 male). The studied cases divided into three groups based on their age and degree of anemia as regard to hemoglobin level according to World Health Organization (WHO) 2002) (table 1). group I: Included patients with iron deficiency anemia (IDA)mild degree. In addition, Group II included patients with iron deficiency anemia (IDA) moderate degree. group III included patient with iron deficiency severe degree. However, Group IV included children apparently health their age ≥5- ≥10 -14 yrs. as control group. All cases were submitted to full history taking, clinical examination, and laboratory investigations. Finally, SB scale was applied before and after treatment. Results: There was statistically significant decrease of hemoglobin, mean cell volume (MCV), mean cell hemoglobin (MCH), serum iron (SI), and serum ferritin in study group when compared to control group. However, there was significant increase of RDW and total iron binding capacity in patients group when compared to control group. In addition, there was significant decrease of information, arithmetic, digit span, verbal IQ, picture completion, picture arrangement, block design, object assembly and total BS in patients group when compared to control group. In study group, iron therapy leads to improvement of mental function in the following parameters (digital span, verbal IQ, picture completion, picture arrangement, block design, object assembly and total SB score. Finally, there was proportional (positive), significant correlation between serum ferritin and IQ before and after iron therapy in patient with iron deficiency anemia (data not tabulated). Conclusion: results of the present study revealed that, iron deficiency anemia had harmful effect on mental function as well as laboratory parameters.