This research was carried out to determine the recovery effect of ozone gas which is thought to be an alternative method for antibiotic treatment in acute clinical mastitis cases. The material of the study consisted of 23 acute mastitis diagnosed mammary lobes belonging to 22 lactating cows breed. Aseptic milk samples were taken before the treatment. The cows in group I received antibiotic by intramuscular route for 5 days, also an antimastitis drug was injected to affected lobes with 24 hours interval for 3 days. 50 mL ozone/oxygen gase was administered via teat duct with an interval of 24 hours for 3 days to group II. Milk samples were taken and bacteriological examination was applied from the cows after 7 days post treatment. The entire bacteria (100%) isolated form the samples of group I was, coagulase negative staphylococci (CNS). Bacterial and clinical recovery rates were 90.90% (10/11), 90.90% (10/11), respectively. The isolated bacteria in group II were 8 CNS (66.66%), 2 CNS+ Candida spp. (16.66%), 2 Streptococci spp. (16.66%). Bacteriologic recovery rates were obtained as 87.50% (7/8) ve 0% (0/2), 0% (0/2), respectively. Clinical recovery rates were determined as 87.50% (7/8), 50% (1/2) ve 100% (2/2), respectively. As a result, it was concluded that, ozone gas was effective on bacteriological and clinical recovery and can be an alternative to antibiotic treatment in acute clinical mastitis cases caused by CNS, but also it was found that it does not have any effect on recovery of Streptococci and Candida spp. caused mastitis cases.