Pregnant cows were given the first injection of an inactivated bovine rotavirus vaccine approximately 4 weeks before calving and a second injection just before calving. This led to the enhancement of rotavirus antibody titers in their colostrum as well as in the milk for at least 5 days after parturition. Thus, when newborn calves were fed with the mammary secretions obtained from the vaccinated cows daily for 5 consecutive days they were fully refractory to experimental infection with 81/36F bovine rotavirus. By contrast, the calves which were given the mammary secretions from unvaccinated cows, had clinical signs consistent with rotavirus infection and viral shedding. Based on these results it is suggested that vaccination of cows according to the scheme followed in this experiment, i.e., two injections within the last month of pregnancy, might be a valid approach which depending on confirmation under field conditions, could help reduce the incidence of rotavirus-induced diarrhea in newborn calves.