To better understand, the effect of dates and pits as immuno stimulant agent and their effects on different species of pathogenic bacteria of animal origin, were investigated In Vivo and In Vitro. In Vivo experimental sixty Albino rats were divided into four equal groups, group one as control, group two fed a basal diet supplemented with 10% minced dates, group three fed a basal diet supplemented with 10% pits, group four fed a basal diet supplemented with 10% mixed minced dates and pits. Phagocytic percent and phagoaytic index were assessed. Also, quantitative detection of immunoglobulins (IgG-IgM) were detected. Immunological investigations revealed significant increase in phagocytic activity of neutrophils in groups treated with dates, pits and mixed compared with control. Also, the same treated groups exhibited (Hyperimmuno-globuinaemia) significant increase in values of immunoglobulins (IgG and IgM) compared with control animals. Also, the direct effects of dates and pits, on different species of pathogenic bacteria of animal origin, were investigated. Test bacteria were selected to represent different species. The tested bacteria included Staphylococcus aureus, Corynebacterium pseudotuberculosis and Bacillus subtilis (Gram-positive) and Salmonella typhimurium, Salmonella dublin and Klebsiella species (Gram-negative). The water extract of pits showed clear inhibition for both Staphylococcus aureus and Corynebacterium pseudotuberculosis until 1/320 dilution. Bacillus subtilis was also inhibited but up to higher concentration (1/40). The effect of concentrated extract was minute on salmobnellae while no effect was detected with klebsiella. On the other hand, water extract of dates showed a detectable inhibitory effect on Corynebacterium pseudotuberculosis until the concentration 1/20. The effect of date extract was minute on Staphylococcus aureus and Bacillus subtilis while no effect was observed against the Gram-negative species. From these results, it can be concluded that date seeds (pits) have a direct inhibitory effect on Gram-positive bacteria while dates had affected Corynebacterium pseudotuberculosis only which is also Gram-positive bacterium. It looks like that it affects the bacterial cell wall composition.