SUMMARY: Bluetongue (bt) virus was isolated from naturally infected cattle with signs similar to those of foot-and-mouth disease. Three cattle, with no serologic or virologic evidence of foot-and-mouth disease, bovine virus diarrhea, infectious bovine rhinotracheitis, or vesicular stomatitis, were purchased and studied clinically, virologically, and serologically. Two were pregnant heifers: one aborted, and bt virus was recovered from the fetus; the other had a live calf of dwarflike conformation and with other congenital deformities. The 3rd, a 3-year-old cow, was extremely emaciated and apparently harbored the bt virus. Evidence indicated that: (1) bt viral strains isolated in these studies have low pathogenicity and immunogenicity for sheep, and (2) bt virus can be isolated from cattle throughout the year as opposed to the usual summer and fall seasons for sheep.