Vitamin D deficiency, which can result from inadequate sun exposure, dietary intake, or problems with absorption, is rarely documented in the rehabilitation literature. Most likely, it is rarely thought of by the rehabilitation profession. This is problematic because vitamin D deficiency can present as musculoskeletal pain, which is commonly seen in both outpatient clinics and inpatient rehabilitation units. The populations with the greatest risk include the homebound elderly, people with pigmented skin, people with cultural and social avoidance of the sun, people who live in wintertime in climates above and below latitudes of 35 degrees, and people with gastrointestinal absorption.Vitamin D deficiency should be included in the differential diagnosis in the evaluation of musculoskeletal pain complaints in the rehabilitation setting, and treatment of any identified deficiency should be considered a potentially important component of the treatment regimen.