Erysipelothrix species were isolated from the tonsils of 79(6.4%) of 1,236 healthy cattle slaughtered in 4 prefectures, Yamagata, Miyagi, Nagasaki, and Tokyo, in Japan from September, 1998, to August, 1999. A combination, modified culture medium consisted of brain heart infusion(BHI) broth containing 0.1% Tween 80, 5% horse serum, 50.MU.g/ml gentamicin, 0.1% sodium azide and 0.001% crystal violet, and BHI agar containing 0.1% Tween 80, 50.MU.g/ml gentamicin, and 0.1% sodium azide was compared with two traditional media for isolation of Erysipelothrix species. The modified media were the most effective since they produced the highest number of Erysipelothrix isolates(p0.01) as well as the greatest degree of inhibition of the growth of contaminated organisms. The isolation rates in summer(10.3%) and spring(7.1%) was higher than those in autumn(2.6%) or winter(1.3%)(p0.01). (author abst.)