In order to study relationship of lactate and the microbial flora in the rumen of ruminal acidosis, lactate, streptococcus bovis, Lactobacilli, Veillonella, Peptostreptococus in rumen of 8 goats which were experimentally overfed with cracked corn, were tested. The results indicate that the concentration of rumen lactate correlates positively with the numbers of strept ococcus bovis and Lactobacilli, but negatively with the numbers of Veillonella and Peptostreptococcus.