Inflammation, cell adhesion to vascular endothelium, and endothelial injury contribute to sickle cell anemia (SCA) vaso-occlusion. Although alterations in inflammatory cytokines and biomarkers have been related, reports have been conflicting, and a conclusive role for these molecules in the disease remains to be established. Furthermore, the effect of hydroxyurea therapy (HU) on the release of inflammatory mediators is not understood. This study aimed to determine plasma levels and leukocyte gene expressions of inflammatory mediators in healthy controls, steady-state SCA patients, and SCA patients on HU therapy. TNF-␣, IL-8, and PGE 2 levels were significantly higher in the plasma of SCA individuals when compared with control individuals. HU therapy was associated with a significant reversal of aug-