Fluorescent antibody staining (FA) for pseudorabies has been performed on frozen sections from the cerebrum, cerebellum, and pons from 51 piglets suspected of pseudorabies. Pseudorabies virus could be demonstrated in the brains of 23 of these pigs both by FA and by rabbit and/or tissue culture inoculation. Most fluorescent cells were found in the cerebral cortex. It is concluded that FA staining may become a reliable alternative to already existing methods for diagnosis of pseudorabies.