We report standards (95th, 50th, and 5th centiles) in Prader-Willi syndrome for weight, height, sitting height, head circumference, head length, head breadth, hand length, middle finger length, palm length, hand breadth, foot length, foot breadth, triceps skinfold, and subscapular skinfold. For comparison with Prader-Willi syndrome standardized curves, normal control data from the literature were plotted similarly and standard curves were produced. We encourage the use of these standards with the examination of patients who have Prader-Willi syndrome and in the comparison of the patient who has Prader-Willi syndrome with other similarly affected individuals. The standards may also be useful for assisting in the diagnosis of Prader-Willi syndrome, particularly in younger individuals.