The pH of the stool and the amount of reducing substances present were observed in 51 normal neonates aged 5 to 8 days. A stool pH of 5 or less was found in 6, 4 of whom were exclusively breast fed. Reducing substances, 0-5% or more, were found in the stools of 16. Stool chromatography in 13 showed lactose, glucose, galactose, or a variable combination of these sugars--that is, a pattern consistent with lactose malabsorption. The stools of 3 infants contained oligosaccharides or maltose only. Chromatography of urine from 60 normal neonates showed detectable sugars in 11 but only 3 had levels above 50 mg/100 ml.