Seventeen infants, 2 to 150 days old, were fed on the dried milk fortified with 130mg percent of lysozyme (Px) for 4 to 21 days. The control infants were fed on Snow Brand Neomilk PF (PF) for 4 to 7 days.<BR>Results obtained are as follows:<BR>1) No difference in general findings, feeding quantity and fecal appearance, was observed between the experimental and the control infants. The experimental infants showed normal weight gain. Especially remarkable weight gain was observed with 5 premature infants.<BR>2) Lysozyme content in feces was increased in 13 cases out of 15 by the Px feeding, although theresults varied widely, in the range of 0.7 to 80mg per 100g solid, from infant to infant. It is, therefore, presumed that lysozyme can pass through the stomach, without receiving any enzymatic decomposition, into the small intestine.<BR>3) Glucosamine content in feces was also increased in 12 cases out of 14 by the Px feeding, although the content varied widely from 0.3 to 4.3mg per g of solid. The tendency of increase was almost the same as lysozyme content of feces.<BR>4) No difference in ammonia-nitrogen, histamine and hydrogen sulfide content in feces was observed between the experimental and the control infants.<BR>5) Nitrogen distribution in feces was determined by the molecular sieving method with Dowex-50 W ion exchange resin. About 60 to 67% of total nitrogen originated from amino acid and other low molecular weight nitrogen compounds. No significant difference in the pattern of nitrogen distribution was observed between the experimental and the control infants. But, amino acid and other low molecular weight nitrogen compounds in feces were slightly increased by the Px feeding. The ratio of water soluble nitrogen compounds to total nitrogen was also increased by the Px feeding.<BR>6) No difference was found in the pH of feces and fecal appearance between the experimental and the control infants. The count of Lactobacillus bifidus in feces, however, increased by the Px feeding.