The therapeutic effect of vaccination with a bacterin produced with Campylobacter fetus subsp.venerealis NCTC 10354 was evaluated in Nelore bulls 5 to 7 years of age. Twenty-seven bulls, that tested positive for C. fetus using the direct fluorescent antibody technique (DFAT), were used in the present experiment. Bulls received two doses of the vaccine separated by an interval of 23 days. After the first vaccination, 15 animals remained positive for C. fetus by DFAT, a significant drop of 44.5% (P<0.05) in the frequency of infected bulls. After the second vaccination, 12 animals were positive by DFAT, a significant decrease of 55.6% (P< 0.05) in the number of infected bulls. There was no significant difference in the number of infected bulls between the first and the second vaccinations. These results showed that vaccination of bulls with a bacterin against C. fetus subsp. venerealis may be an important additional strategy to control bovine genital campylobacteriosis.