It has been recognized that cattle are the main source of Escherichia coli O157:H7. This organism appears to be confined to the gastrointestinal tract and is shed in the feces. A probiotic product containing lactic acid-producing Streptococcus bovis LCB6 and Lactobacillus gallinarum LCB12 isolated from adult cattle was developed, and a preliminary experiment was conducted to evaluate its effect on the elimination of E. coli O157 from experimentally infected calves. Eight 4-month-old Holstein calves were orally challenged with E. coli O157 and the probiotic product was administered to 4 calves with continuous fecal shedding of E. coli O157 at 7 days after the infection. Fecal shedding of E. coli O157 was completely inhibited and re-shedding was not detected in any of the animals. Remarkable increase of the concentration of volatile fatty acids (VFAs), especially acetic acid in the feces after the administration of probiotic bacteria was correlated with the decrease in the number of E. coli O157. In the 4 calves in which fecal shedding of E. coli O157 had spontaneously stopped by the 7th day, a high concentration of VFAs was detected in the feces before and after the experimental infection. Although our results are preliminary and obtained from calves under limited conditions, the possibility of using a probiotic product to reduce fecal shedding of E. coli O157 from cattle was suggested.