• Subject height and lower esophageal sphincter location were determined in 213 children and adults to determine whether the anthropometric variable could be used to accurately predict sphincter location across all age ranges. The upper margin of the lower esophageal sphincter was determined with a nasally placed manometry catheter. Height was highly predictive of lower esophageal sphincter location across all subject groups (r2 =.96) and in the youngest subset of subjects (≤2 years of age, r2 =.88). The predictive ability of height remained significant but progressively decreased in the four older subject groups (>2 and ≤10 years of age, r2 =.74; >10 and ≤20 years of age, r2 =.66; >20 and ≤40 years, r2 =.58; and >40 years, r2 =.49). The regression equation that described subjects 2 years of age or younger (L=0.22[H]+4.92, where L is the location in centimeters from the nares and H is the height in centimeters) correctly predicted lower esophageal sphincter location within 1.0 cm in 90% of these subjects. In the older subject groups, predicted lower esophageal sphincter location was in error by greater than 2 cm in 25% to 35% of the subjects, even when age group—specific regression equations were used. Decreased predictive ability related to both increasing age and increasing height. We conclude that lower esophageal sphincter location can be predicted from height in subjects up to 2 years of age. The prediction is sufficiently accurate in this age group to allow placement of pH probes without manometric measurements.