Studied were some of the humoral and cellular factors of immunity with calves experimentally infected with Herpes virus 1. The clinical signs manifested by the infected calves were followed up for 10 to 12 days. The shedding of the virus through the nasal mucosa was demonstrated up to the eighth day, the peak values reached being between the 3rd and 5th day of infection. Demonstrated was blastic transformation in vitro with a phytohemagglutinin of the lymphocytes obtained from the peripheral blood prior to infection; the same phenomenon was observed also with each sample taken from the peripheral blood of the controls. Blastic transformation of lymphocytes was demonstrated also with the use of a specific antigen with the group infected from the 6th to the 15th day, with highest indices between the eighth and tenth day. This spoke of the presence of an immune response. The humoral immune response, followed up in its dynamics, was manifested by the presence of local antibodies in the infected calves first on the eighth day, and of serum antibodies on the 12th day. The results obtained point to the importance of both components of immunity with calves. It is of interest to note that the peak of the cell response set in on the eighth to ninth day of infection which coincided with the cease of virus shedding. On the other hand, the serum antibodies were demonstrated later--between the eighth and the twelfth day. This data showed that cellular immunity played a greater part in the recovery of calves in the case of a primary Herpes virus 1 infection.