In this study, feeding fermented colostrum to Holstein calves was investigated to find out the effects on their growth and inhibition of diarrhea. The results of this study showed that the mixture of L. rhamnosus and E. faecium would be proper bacteria for fermentation of colostrum because of favorable odor, inhibition of coliform bacteria and high number of lactic acid bacterial count. Among the groups of calves fed 0, 5, 10 and 20% of fermented colostrums, average body weight gain for 28 days on feeding fermented colostrum were 16.6, 16.6, 17.4 and 18 kg, respectively showing that calves fed 20% fermented colostrum achieved the highest body weight gain. Occurrence of diarrhea due to feeding various levels of fermented colostrum was also recorded. Three calves out of 5 suffered diarrhea in 0%, 5%, and 20% group, on the other hand, all 5 calves suffered diarrhea in 10% group. Diarrhea persisted for durations were 2.7, 2.4, 4.0, and 2.4 days in 0, 5, 10, and 20% group, respectively. Fermented colostrum did not prevent the occurrence of diarrhea. In overall, addition of fermented colostrum above 10% level showed favorable effects in gaining body weight under the conditions of adding more portions of the fermented colostrum either for 14 days or longer feeding period of the fermented colostrum. On the other hand, fermented colostrum showed no beneficial effect in prevention of diarrhea in this study.