Based on a glycoprotein E (gE) deleted bovine herpesvirus - 1 (BoHV-1) Abu Hammad strain, a modified live virus as well as an inactivated virus marker vaccine have been developed that allow differentiation between immunized and BoHV-1 infected cattle. These vaccines were evaluated for safety and efficacy in calves and compared with the commercial locally prepared inactivated BoHV-l vaccine. No adverse effects were observed in any of the calves vaccinated with the gE-negative vaccines. Both gE negative and the commercial inactivated vaccines revealed a significant increase in humoral immune response at 3rd week post booster vaccination no significant change could be detected among them as detected with serum neutralization test (SNT) and indirect enzyme-linked immunosorbent assay (ELISA). After vaccination, calves vaccinate with gE-negative vaccines did not produce antibodies against gE, but these antibodies were detectable within 2 weeks in vaccinated calves with a local prepared inactivated BoHV-l vaccine as demonstrated using gE-blocking ELISA to detect antibodies against gE. These results demonstrate the efficacy of a gE-negative BoHV-l vaccine and the detectability of antibodies against gE. The combined use of the marker vaccine and the gE-blocking ELISA makes it possible to differentiate between vaccinated animals and infected animals. This possibility may be very useful in BoHV-l control programmes