The concentration of plasma interleukin-33 level has not been estimated in any studies conducted in patients with sickle cell disease (SCD); hence, we investigated the levels of plasma interleukin-33 in patients with sickle cell disease with or without ONFH to assess whether it can be used as a marker for the early detection of ONFH in this disease also. The gene discussed is IL33; the disease is Schnyder corneal dystrophy.