In addition to reduction of milk yield and health problems, behavioural abnormalities were observed in a herd of dairy cows maintained in close proximity to a TV and radio transmitting antenna. Evaluation of possible factors which could explain the abnormalities in the live stock did not disclose any factors other than the high-frequency electromagnetic fields. An experiment in which a cow with abnormal behavior was brought to a stable 20 km away from the antenna resulted in normalisation of the cow within five days, whereas symptoms returned when the cow was brought back to the stable nearby the antenna. In view of the previously described effects of electromagnetic fields, it might be possible that the observed abnormalities in cows are related to the electromagnetic field exposure.