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(p<0.01) 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%)(p<0.01). (author abst.)