In order to define the normal values of steatocrit during the first 3 months of life and the normal correlation between fecal fat content and steatocrit values, 60 full-term healthy unweaned infants (30 bottle-fed, 15 breast-fed, and 15 mixed-fed) were studied. The steatocrit micromethod was performed in these babies at 7, 14, 21, 28, 45, and 90 days after birth. Steatorrhea often occurs during the first month and then decreases, as shown by the fall in the steatocrit curve from 7th to 28th day in our subjects; at 45 days, few babies have steatorrhea. The 90th percentile profile of steatocrit values shows a value of 25% at the first week of life and a value of 13% at the fourth week. After the end of the third month, babies with steatocrit values higher than 2% should be put under close observation. Moreover, fat absorption can be greatly influenced by diet; in breast-fed babies, steatorrhea disappears more rapidly and steatocrit values are lower at every age than in partly or totally formula-fed babies. The good correlation between steatocrit values and fecal fat content (r = 0.97) confirms that this micromethod can be used for monitoring steatorrhea instead of other more cumbersome and expensive methods.