PURPOSE: The normal distribution of exophthalmometry measurements in a U.S. pediatric population was determined as a reference for clinical practice. METHODS: This was a cross-sectional study, in which 673 normal subjects, between 1 and 17 years of age, randomly selected from patients presenting to our institution, were measured with an exophthalmometer. Normal volunteers also participated at a booth at the annual state fair. Subjects were excluded for a prior history of orbital tumor, craniofacial anomaly, thyroid disease, orbital trauma, or inability to tolerate the measurement. RESULTS: A total of 673 subjects (52% female) with a mean age of 9.6 years were studied. There was no difference in exophthalmometric measurements between male and female subjects. Mean exophthalmometric measurements increased with age: less than 4 years old (13.2 mm), 5-8 years old (14.4 mm), 9-12 years old (15.2 mm), and 13-17 years old (16.2 mm). Asymmetric measurements occurred in 100 (14.9%) subjects, with a 2-mm maximal difference in 2 subjects. CONCLUSION: Exophthalmometric measurements vary with age among the pediatric population. Reference data are presented for each age group in a U.S. cohort.