AbstractDown syndrome (DS) is one of the most common chromosomal conditions that results in intellectual disability. Children with DS have many different inflammatory and noninflammatory conditions that can affect joint mobility leading to arthralgia and altered joint range of motion (ROM), and it is important to have normal reference values for comparison to determine the degree of impairment. The objective of this study was to establish normative joint ROM values, using a standardized measurement approach, for upper and lower joints of healthy children of both genders with DS. This study evaluated joint ROM in healthy males and females with DS who had no previous musculoskeletal pathology. Younger males have more ROM than females at the same age and both genders lose ROM with age but continue to have increased ROM in the ankles compared to children without DS. This study establishes optimal estimates of joint ROM in children with DS, and this information should be helpful to clinicians when assessment requires evaluation of joint ROM to know if evaluation falls within the normal ROM. This reference should be helpful to track joint disease progression over time or as part of a musculoskeletal screen for abnormal joint ROM in children with DS.