The results of a 30-year research activity in the field of animal virus diseases performed in the "Stefan S. Nicolau" Institute of Virology are briefly reviewed. Investigations referred to swine pest, fowl pest, Newcastle disease, fowl pox, sheep pox, Aujeszky's disease, Rubarth virus, foot-and-mouth disease, chlamydial infections, etc. Mention is made of the preparations obtained for the specific prophylaxis of most of these diseases.