Abstract Prader-Willi Syndrome is a genetic disorder resulting from the lack of paternal expression of the 15q11,2-q13 chromosome with an estimated prevalence of 1/10,000-1/30,000.Gastrointestinal complaints are common in patients with Prader-Willi Syndrome, with an estimated 25-30 percent of those suffering from constipation. This case report examines an 18-year-old female with Prader-Willi Syndrome who presented with the complaint of chronic constipation. The use of osteopathic manipulative treatment (OMT) resulted in a significant improvement of this patient's bowel function. The authors theorize that osteopathic manipulative medicine could be useful as an adjunct therapy to pharmacologic intervention for chronic constipation in patients with Prader-Willi Syndrome.