Horses have been shown to have the deadly genetic condition calledsevere combined immunodeficiency (SCID). Animals with the condition are unable to produce specific antigens for immunological responses as a result, they become extremely vulnerable to pathogenic pathogens and die before six months.The control and responses to pathogens of neonatal and young foals immune responses differ from those of adults. The purpose of this study to determine carrier of SCID gene in Arabian foals and mares in addition assessing cellular and humoral immunity in Arabian foals and mares. Thirty-eight, Arabian foals and mares were examined.Hair samples were examined for detection of SCID gene by fragment analysis. While blood samples were collected for erythrogram and leukogram. Also, immunoglobulins including Ig E, Ig G, Ig A and Ig M. Also, SAA and fibrinogen were measured in serum and genes expression using Real Time-PCR were performed for IL-10, IL-6, TNFα and TLR 4 mRNA. All samples were homozygous and free from SCID gene. RBCS and monocytes showed significantly high value in foals compared to mares while, there were significant high value in MCV, IgG, IgM, IL-10, IL-6, TNF-α, TLR 4 mRNA expression in mares compared to foals. SAA and Fibrinogen showed non-significant difference in mares and foals.SCID diagnostic tests will aid in breeding programme selection to prevent carrier-to-carrier mating. Also assessing immunity in mares and foals is very important tools to determine the optimal immunological pathways and provide fresh preventative measures to ward off contagious diseases.