Sickle cell anemia is a hemoglobinopathy caused by a mutation that results in the production of an abnormal hemoglobin molecule, hemoglobin S (Hb S). This is responsible for profound physiological changes, such as the sickling of red blood cells. Several studies have shown that hydroxyurea protects against vaso-occlusive crises.The aim of this study was to evaluate the oxidative stress associated with biochemical parameters in patients with sickle cell anemia treated with hydroxyurea.The study was conducted with 20 male and 25 female patients at the Hospital Universitário Walter Cantídio. The patients were divided into two groups: a study group (n = 12), patients with sickle cell anemia who were receiving hydroxyurea and a control group (n = 33) of sickle cell anemia patients not submitted to hydroxyurea treatment. The biochemical parameters analyzed were ferritin, transferrin, and serum iron. Glutathione was measured in its reduced form to analyze the oxidative state.The results showed insignificant increases in the levels of serum iron, transferrin and ferritin in patients treated with hydroxyurea when compared with those who did not take the medication. However, the glutathione levels were significantly higher in patients taking hydroxyurea than in controls.These results indicate that hydroxyurea possibly acts as an antioxidant by increasing glutathione levels.