Investment of 12,900 € in vaccination and its implementation facilitated lower costs associated with the treatment of clinical mastitis (-14,199 €), a higher milk value (+39,075 €) and a reduction in the SCC, which contributed to the improvement in production (+11,269 €). The greatest return on this farm was the increase in quality premiums (61%) followed by the costs associated with mastitis (22%) and the reduction in SCC (17%). The ROI obtained after the investment was 500 % (64543/12900 x 100).