Case-control studies were carried out in 19 dairy cattle herds where infectious bovine rhinotracheitis and bovine viral diarrhea-mucosal disease were present and 9 herds free from both diseases. To confirm the disease appropriate number of cows (by expected prevalence 30%, level of confidence 95%) older than 24 months were bled in each herd and serologically tested to BHV-1 and BVDV infections using ELISA tests. Questionnaires on the occurrence of main clinical signs of BHV-1 and BVDV infections in cattle were also conducted. Analysis of clinical presentations reported by the farmers revealed that abortions and fetopathies as well as emaciation both in calves and in adult cattle were significantly (p < 0.05) more often observed in seropositive than in seronegative herds.