Present study is aimed to determine the excretion of Brucella abortus organisms in milk of vaccinated lactating cattle and buffaloes. All experimental lactating animals in early and mid-stage of lactation were vaccinated with Brucella abortus S19 reduced dose vaccine through subcutaneous route. After vaccination daily milk samples from all the animals i.e. 10 cattle and 10 buffaloes were collected in sterile sample collection vials from day 1 till day 30 for bacteriological analysis. Milk collected from all vaccinated animals was not used for human consumption and was discarded throughout the study period. Sterile Potato infusion agar (PIA) media plate was used for detection of Brucella abortus organisms. For identification of contaminants BDBBL Crystal ID (Becton, Dickinson and Company) was used. All the experimental lactating animals were serologically negative for brucellosis at the time of enrollment. Milk samples from the animals that were collected and tested up to 30 days, were found negative for Brucella abortus in microbiological culture, although in all of the milk samples, contamination was observed.