843 Introduction: Although deaths among children with sickle cell disease (SCD) have decreased substantially in the United States and Europe, high mortality is still a serious problem in most developing nations. Common causes of death in children with SCD include sepsis, splenic sequestration, stroke, and acute chest syndrome (ACS). Hydroxyurea therapy is able to reduce mortality in adult patients with SCD, but no data exist regarding its benefits on mortality among pediatric patients. Since 2000, our center has prospectively offered hydroxyurea to children with SCD who meet criteria established by the Brazilian Ministry of Health. These criteria include: all SCD genotypes ≥3 years of age, with ≥2 ACS or ≥3 painful events in the previous year, persistent oxygen saturation 200 cm/sec, or overt stroke with transfusion contra-indication or family refusal. Methods: We retrospectively collected morbidity and mortality data for the first 10 years of the hydroxyurea therapy program of the Hematology Institute of Rio de Janeiro, Brazil (HEMORIO). We compared clinical and survival outcome among hydroxyurea-treated and untreated children, but since hydroxyurea was offered only to children ≥3 years of age, all analyses were restricted to patients 3–18 years old. The incidence of clinical events (hospitalization, ER visits, and transfusions) in the 12-month period prior to initiation of hydroxyurea was compared to that during the first year of treatment using the t-test, while survival analyses were done using the Log Rank Test. Results: Since 2000, 1643 children with SCD (1223 HbSS or HbSβ0-thalassemia, 291 HbSC, 35 HbSD, and 94 HbSβ+-thalassemia) were prospectively followed at our Center; 59% males, median age 7.7 years. Of these, 965 were between the ages of 3 and 18 years, and were therefore included in the analysis. A total of 224 patients (205 HbSS or HbSβ0-thalassemia, 7 HbSC, 3 HbSD, and 9 HbSβ+-thalassemia, 131 males) met criteria to initiate hydroxyurea treatment; median age at initiation was 6.0 years (range, 3.0–17.6). Hydroxyurea was started at 15 mg/kg/day, and escalated to a maximum of 30 mg/kg/day, or less if hematologic toxicity. Monthly visits were performed during dose escalation and then every 2–3 months, equivalent to patients not receiving hydroxyurea. The median treatment duration for the hydroxyurea-treated group was 1.9 years (range, 1.2 – 6.1) and median hydroxyurea dose was 20 mg/kg/day (range, 15 – 28). There was a significant reduction in hospitalization (67.9%, p=0.002), emergency room visits (48.7%, p Conclusions: These data indicate that 1) mortality for SCD remains high among Brazilian pediatric patients; (2) hydroxyurea therapy for clinical indications is feasible among young patients in Brazil and reduces incidence of acute events; and 3) hydroxyurea therapy may reduce mortality among children with SCD. Despite having a more severe clinical course, hydroxyurea-treated patients had a lower...