The aim of this study was to characterize the acute complications that required hospitalization in children under 5 years with Sickle Cell Disease. The population included 70 patients, 64% of African ascendency and 95.7% homozygotic for the HbS. We analyzed data from 337 hospitalizations. The first hospitalization occurred before 12 months in 38.6% and the average hospital admission per child was 3.92. The mean duration per hospitalization was 5.36 days. The most common diagnosis was vaso-occlusive crisis (36.8%) followed by fever, upper airway infections, bacterial pneumonia and splenic sequestration. Hemoglobin values at admission were between 6 and 7 g/dL in 22.3%, with 44.2% requiring at least 1 blood transfusion. There are several acute complications of SCD, being vaso-occlusive crisis the most common. Splenic sequestration generally occurs during the first 2 years and is associated with the need of transfusion. They represent a significant burden, with each child spending approximately 3 weeks hospitalized.