The nucleotide sequence of the S gene of the bovine respiratory coronavirus (BRCV) strain G95, which was isolated from nasal swabs of a calf suffering from respiratory disorders, was determined and compared with the S gene of the enteropathogenic bovine coronavirus (BECV) strain LY138. Sequence analysis revealed 98.7% nucleotide and 98.3% deduced amino acid identities between the S genes of BRCV-G95 and BECV-LY138 without any deletions or insertions. Nucleotide substitutions were distributed randomly throughout the gene. Five monoclonal antibodies specific for the S protein distinguished BRCV-G95 from BECV-L9, but failed to differentiate it from BECV-LY138 in Western blots under denatured and native conditions. BRCV-G95 induced cytopathic changes in cell cultures that were similar to BECV-LY138 but different from BECV-L9. These results suggest that strain BRCV-G95 is more closely related to the virulent strain BECV-LY138 than to the avirulent, cell culture-adapted strain BECV-L9.