_ Journal of the Egyptian Society of Parasitology, Vol. 28, No.3, J. Egypt. Soc. Parasitol., 28 (3), 1998: 899-906 studies on prenatal infections in children with unknown cause of mental retardation and their mothers, by Mohamed A.Marei,Azza M.S.Al Hamshary Osama a. fatoh and Sohir Abdel Rahman , Dep[artment of pediatrics ,Parasitology and Clinical Pathology,Faculty of Medicine,Benha branch of Zagazig University,Benha ABSTRACT Specific IgG antibodies against Toxoplasma,rubella,cytomegalo-virus and herpes simplex (TORch agents) were investigated in 32 infants and children with unknown cause of mental retardation (MR) and their mothers.16 mentally normal infants and childrens of the same ages and their mothers were chosen as controls.Specific Toxoplasma IgG antibodies werw 43.75% and 37.5% for the MR patients and their mothers .specifif rubella IgG antibodies were 56.25% and 81.25% for the MR patients and their mothers ,for CMv IgG antibodies were 75% and 81.25% and for herpes simplex IgG antibodies were 18.75% and 25% respectively.A total of 93.75% showed antibodies positivity to one or more of the pathogenic agents.