Sensitivity and specificity of two ELISA systems for the detection of antibodies to Bovine Herpes-virus 1 (BHV1; IBR/IPV) were tested by using 214 sera of cattle with predetermined history of BHV1 infection and freedom from BHV1 infection, respectively. With these sera as "gold-standard", the sensitivity of ELISA1 (HerdCheck: Anti-IBR) appeared to exceed 98%, whereas for ELISA2 (Checkit: Trachitest) a sensitivity of between 94 and 99.3% was determined. The specificity of ELISA1 amounted to at least 96.9%, whereas for ELISA2 it ranged apparently from 81.5 to 98.5%. When applied in routine testings of serum samples, the two ELISA systems correlated extremely well. With each test, only 3 of 1431 samples gave contradictory results. In all these cases, alternative tests suggested that the contradictions represented false-positive reactions. A similar correlation was observed when milk samples in the place of sera were probed. The serum and milk samples were additionally tested using two corresponding ELISA systems (obtained from the same manufacturers) for the detection of antibodies to Bovine Leukemia virus (BLV). The sensitivity and specificity of these tests could not be determined because of lack of samples with known history of infection. The results of the tests, however, correlated very well. Only 6 of 1431 sera reacted in a contradictory way. These observations indicate that the kits tested in this study, both for the detection of antibodies to BHV1 and to BLV, meet high quality standards. Possibilities to improve the kits were still detected.