An experiment was conducted to study the effects of feeding milk fermentation by-product (MFBP) and probiotics on the growing performance and prevention of diarrhea of the growing pigs. In this experiment 144 heads of three-way crossbred (Landrace x Large White x Duroc) growing pigs weighing approximately 11 ㎏ were employed into six treatment groups consisted of control. MFBP-A, MFBP-B, Streptococcus faecium, bacillus toyoi and antibioties (colitracin) for about 7 weeks of experimental period. The results from the present study were summarized as follows. 1. Average daily gain (P $lt; 0.01) and feed efficiency (P $lt; 0.05) of MFBP-A, MFBP-B, probiotics and antibiotics fed groups were significantly better than those of control group. However, it was found that there were no significant differences among the experimental groups, The amount of feed consumed per pig a day was not altered by the addition of MFBP, probiotics and antibiotics. 2. Incidence of diarrhea, although without significant difference, was slightly reduced by supplementing MFBP, probiotics and antibiotics in the young growing pigs. 3. Pigs fed MFBP and probiotics utilized the dietary protein and fat more efficiently, although statistical significance was not detected. In conclusion, it may be suggested firstly that probiotics and milk fermentation by-product can improve the growth rate and feed efficiency of pigs, and secondly that these effects are possible through (1) improvements in nutrient utilizability and nitrogen retention and (2) diarrhea prevention. Therefore, it could be inferred that the milk fermentation by-product can be used as a feed additive for growth promotion and diarrhea control in the young growing pigs as have been probiotics already marketed.