During 20 months of the 1987-1990 period, lung tissue samples from 351 calves were obtained at a slaughterhouse. These calves were from counties nearby Porto Alegre. The direct and indirect fluorescent antibody tests (FAT) using polyclonal and monoclonal antibody conjugates were performed on frozen lung sections. Eighteen (5.13%) of the calf lung samples were positive for the Bovine Respiratory Syncytial Virus (BRSV). The BRSV was isolated from FAT positive samples.