This study was designed to investigate the protective effect of non porin outer membrane proteins (OMPs) of Salmonella typhimurium and O-specific polysaccharide (OSP) of E.coli as conjugated vaccine against salmonellosis. One hundred urine samples were collected from patients with UTI. E.coli was isolated, identified by performing some biochemical tests and API E system and O-specific polysaccharide was extracted by phenol hot water method. The outer membrane proteins (OMPs) of S. typhimurium was extracted and analyzed by Sodium Dodecyl Sulphate-Polyacrylamide Gel Electrophoresis (SDS-PAGE) after performing microscopic examination, some biochemical tests and API E identification for S. typhimurium that was isolated previously from stool of infants suffering from diahrria. Results of protein profile of the S. typhimurium outer membrane proteins revealed that bands with molecular weight ranged between - kDa were present. Purification by ion exchange chromatography on DEAE- cellulose was carried out. Results of protein profile of the purified OMPs by (SDS-PAGE) exhibited that two bands with molecular weight kDa and KDa were present. E.coli polysaccharide was conjugated with OMPs by reductive amination method. OMP-PS conjugate was isolated by gel filtration on Sephacryl S- and analyzed by SDS- PAGE. Results recorded that two bands with MW and were present. To evaluate the immunological effects (Total and absolute counts of leukocytes and IgG titer level) and histopathological (Intestine, liver and spleen) changes against S.typhimurium and E. coli, fifty albino mice were divided into ten groups before subjection to various treatments Group : (negative control), Group : (positive control, S.typhimurium), Group : (positive control, E.coli), Group : mice treated with OMPs-PS conjugate, Group : mice treated with OMPs-PS conjugate and infected with S.typhimurium, Group : mice treated with OMPs-PS conjugate and infected with E.coli, Group : mice treated with non-porin OMPs, Group : mice treated with non-porin OMPs and infected with S.typhimurium, Group : mice treated with E.coli polysaccharide and Group : mice treated with E.coli polysaccharide and infected with E.coli Results of immunological and histopathological parameters were as follows: Immunization with OMPs-PS conjugate and infection with S.typhimurium led to a significant increase in total leukocytes count as compared with positive control (S.typhimurium). Mice treated with OMPs-PS conjugate then infected with E.coli exhibited a significant decrease in total leukocytes count as compared with positive control (E.coli). Treatment with OMPs-PS conjugate led to a significant increase in lymphocyte count after infection with S.typhimurium and a significant decrease in lymphocyte count after infection with E.coli. Higher IgG levels were recorded in mice treated with OMPs-PS conjugate then infected with S.typhimurium or E.coli. Vaccination with OMPs-PS conjugate led to ameliorate the histopathological effect of S.typhimurium and alleviate the effect of E.coli on intestine, spleen and liver.