Fifteen pregnant cows were inoculated subcutaneously and intravenously between 101-147 days of gestation with the wild-type Wesselsbron disease virus. In addition, 2 foetuses were injected directly through the uterine wall after surgical exposure of the pregnant horn. The clinical symptoms, viraemia and serology in the cows are reported, as also the gross- and histopathology and the virological and serological results of the calves and foetuses. Abortion was not an important manifestation of experimental Wesselsbron disease in cows, as it occurred in 3 animals only. Apart from a short temperature reaction in some cows no other clinical symptoms were recorded. A viraemia was not always present in these cows and, when detected, was of low magnitude and short duration. One cow, in which the foetus was inoculated at 115 days of gestation, aborted at 231 days. The foetus showed marked porencephaly and cerebellar hypoplasia.