Sickle cell disease results in significant morbidity and mortality for those affected with this disease. Despite the fact that every case of sickle cell disease results from the same genetic mutation, there is considerable heterogeneity in the clinical course of the disease. Considerable knowledge has been gained regarding the complications of sickle cell disease including pain episodes, infections, stroke, and lung disease. Clarifying the clinical course of sickle cell disease has enabled us to develop therapies to decrease the morbidity of this disease and, with hope, will direct further investigations into novel treatment interventions.