A total of 231 strains of Listeria organisms have been isolated during the last 14 years from adult sheep, lambs, fetuses, and ensilaged forage. Their differentiation have shown that 67 of them belong to the 1 st serotype, 77 -- to 4 c, and 26 have been determined as strains of the 5th serotype. The biochemical study on 170 of the strains have revealed that: more of them, belong to the 1 st, 4 c, and 5 th serotype break down dextrose, trehalose, levulose, salycin, esculin, ramnose, and glycerin. They do not produce hydrogen sulfide and indol, do not liquefy gelatin, and are negative for adonite and inulin. Not all prove catalase-Foges-Proskauer- and methylred--positive.