Background: Sickle cell disease (SCD) is a form of haemoglobinopathy which affects the structure of the haemoglobin by genetically substituting Valine for Glutamate at position 6 of the amino acid linear sequence of the protein. In SCD, oxidative stress is increased and believed to play a significant role in the pathophysiology of SCDrelated crisis. It has been found that a structural mutation of thymine (T) to cytosine (C) substitution in the coding sequence of manganese-superoxide dismutase (Mn-SOD) gene, which changes the amino acid codon at 9th position in the signal peptide from valine (GTT) to alanine (GCT), is implicated in various disease states.Aim: This work was aimed at investigating the relationship between oxidative stress and genetic polymorphism of manganese-superoxide dismutase in patients with SCD visiting the