The present work was performed to study the effect of garlic on blood haematology, biochemistry and immunity of healthy and infected chickens and correlate it with the histopathological changes in the different organs. Also to investigate the possibility garlic as antibacterial food additive in chicken ration. The studyincluded 3 experiments. The first one (Healthy chicks) comprised 60chickens subdivided into 4 groups. The 1st group kept as healthy control, the 2nd and 3rd group received ration contained 2% and 40/0 fresh garlic respectively daily for 6 weeks, while the 4th group received ration contained 20/0 garlic powder daily for 6chickens subdivided into 3 groups, the s” group kept as infectedcontrol group which received normal ration and infected with Cl.Perfringens type ”A” at 3 weeks old. The s” and ih group wereprophylacted by receiving ration contained 2% and 40/0 fresh garlicrespectively from one day old till the end of the experiment andinfected at 3 weeks old with Cl. Perfringens type ”A”. The thirdexperiment (Infected and treated chicks) comprised 20 chickenssubdivided into 2 groups, the 8th and 9th group were received normal