Antibacterial efficacy of garlic extract was studied in vitro and in vivo. This was judged on the basis of in vitro inhibition of microbial growth of isolated microorganisms on blood agar and the recovery of clinical cases of endometritis by intrauterine infusion of garlic extract. Bacteriological samples before and after treatment were taken from 15 cows affected with 2nd and 3rd degrees of endometritis. Initial bacterial count ranged from 108 to 1012 Colony forming units / ml (cfu /ml) before treatment was markedly reduced after garlic treatment to be 103 to 104 cfu/ml. The isolates were cultured on blood agar media with different concentrations of garlic extract ( 2,3,4,5,6,7,8%). Concentration of 8% inhibited all isolated strains. The in vitro study revealed a constant pH value of 5.8 by incubation at 37 ° C for one hour. The activity of garlic extract was found 18 times neomycin sulphate . The in vivo investigation disclosed that all the cows having 2nd degree endometritis responded well after single intrauterine infusion of garlic extract. All the cows showing 3rd degree endometritis required two infusions of the garlic extract for complete clinical recovery.