In a retrospective study of fifty-four cases of sheep (n = 40) and goats (n = 14) diagnosed as cerebral listeriosis, we reevaluated the histological lesions and used a silver stain as well as immunohistochemistry to demonstrate the listeriae in the tissue. Perivascular cuffs consisting of mononuclear cells, focal purulent lesions (microabscesses) and/or focal accumulation of macrophages (glial nodules) in the caudal brain stem (medulla oblongata and pons) were considered as pathognomonic. In 87% of the cases the organisms could be visualized within the focal lesions both by silver stain and by immunohistochemistry with comparable sensitivity. They were most numerous in microabscesses and often in very low numbers or absent in glial nodules. Bacterial organisms were absent or very rarely found in the meninges and in the perivascular cuffs. In only eight out of eighteen cases Listeriae (L.monocytogenes) could be cultered, sometimes only after 4 weeks of incubation at 4 °C. We conclude that listeriosis in small ruminants can be diagnosed histologically with high reliability, but negative isolation results by culturing do not exclude listeriosis.