Blood samples were collected from 2892 cows and heifers of various ages from 95 dairy farms in the Kanton of St. Gallen and were tested for antibodies against bovine virus diarrhea. The percentages of seropositive, seronegative and inconclusive cases were 83.7%, 13.0% and 3.3%, respectively. In all herds, at least one case was seropositive, and in 29% of the herds, all the animals tested were seropositive. On a herd basis, the seroprevalence ranged from 16.2% to 100% with a mean (+/- SD) of 85.8 +/- 17.6%. The seroprevalence in one to two-year-old heifers was not significantly different from that of the entire sample.