Background: Determination of fecal pancreatic elastase 1 (E1) is a reliable and noninvasive test of exocrine pancreatic function. Adult reference values of greater than 200 μg E1/g feces do not seem to be applicable to early infancy because of immature pancreatic function. Because reference values for infants do not exist, the current study was aimed to define reference values for preterm and term infants up to 12 months of age. Methods: The authors measured pancreatic E1 concentration in feces of 148 infants up to 12 months of age. Infants with known bowel or pancreatic disorders were excluded from the study. Results: The authors found that 96.8% of all children had E1 concentrations greater than an adult lower limit after 2 weeks of life, independent of gestational age. Up to 48 hours after birth, none of the preterm infants had an E1 concentration of greater than 30 μg/g meconium, whereas 43% of the term infants had normal adult values. Conclusions: The adult reference value for pancreatic E1 of greater than 200 μg/g feces can be applied to infants older than 2 weeks, independent of gestational age, birth weight, and the type of nutrition.