Sixty four infants (25 males and 39 females), including 9 under nour- ished and 4 prematures, were fed with a commercial spray dried soybean milk preparation, while 32 (17 males and 15 females) were fed with a whole cow's milk powder diet, and 48 (24 males and 24 female) were fed with either human milk or fresh cow's milk. There were 5 pairs of twins, one of each pair was fed with the soybean preparation; and among the other 5, 2 were fed with cow's milk powder diet and 3 were fed human milk.The ages of the infants at the start of the observation were. 41 under one month, 76 at two months, and 28 at three months. Their ages at the conclusion were all one year.Twenty five mg of ascorbic acid and 1-2 drops of concentrate fish liver oil, furnishing 5000 I.U. of vitamin A and 500 I.U. of vitamin D, were supplied daily to all infants from the very beginning. Foods, including egg yolk, rice porridge, wheat flour noodles, soybean curd, chopped meat or vegetables etc were supplemented at the proper ages.Infants fed with the soybean milk product all had goo'd appetite, and no digestive disorder. Most of them passed formed stools once or twice a day. Only a few passed thin stools 5-6 times a day at the beginning, and changed to excrete formed stools after three weeks.The average daily calorie intake of the normal infants fed with the soybean product at the age of five months was 107 kcal; the prematures took 144 kcal, while the undernourished took 147 kcal.The growth rate of the infants fed with the soybean product was normal; the average growth curve is below that of infants fed with cow's milk powder diet or human milk before the 7th month, and there is practically no difference between the three curves after this age.Among the twins, those who took the soybean product all grew better in height and weight than their siblings.The average age of the eruption of the first tooth of the infants in the three groups were all at the 7th month. The blood hemoglobin and red cell count of the infants in the three groups were all normal.As to the serum alkaline phosphatase activity, 3.3% of the infants in the soybean food group and 12.5% of the infants in the human milk group were above 15 Bodansky units at the beginning, and all fall below 15 units at the end of the observation.X-ray photographs of the long bone at the beginning revealed that, among 55 infants, there were 4 had signs of rickets, 3 had doubtful rickets in the soybean food group, 48 had doubtful rickets in the human milk group. No signs of rickets were observed in the three groups at the end.It may be concluded that the nutritional quality of the spray dried soybean milk preparation seems to be equal to, if not better than, that of whole cows milk powder or human milk.