Herpesvirus infections in solipedes animals are some of the worst infections due to their more often chronicle course and longer period of virus carrying on the part of infected animals. With regard to making a quick and exact diagnosis the direct electron microscope and immunoelectron microscope methods were tried. The results lead to the conclusion that the direct electron microscope method is a particularly valuable and an exceptionally fast method for spotting and proving the existence of herpesviruses in horses in suspensions obtained from the organs of aborted mare foetuses or dead animals. Through it an early diagnosis may be made as soon as the third hour after the incoming of the material. The immunoelectron microscope method is more sensitive and exact, but requires a longer period of time and preliminary preparations of laboratories. It can be used successfully for making an exact diagnosis in cases where the results acquired by using other laboratory methods are doubtful.