Objective: To analyze the use of attended polysomnography (PSG) and home sleep testing (HST) in patients with Hypermobility Spectrum Disorder (HSD). Background: Sleep Disordered Breathing (SDB) is common in patients with Hypermobility Spectrum Disorder (HSD). Attended Polysomnography (PSG) is more sensitive than Home Sleep Testing (HST) to the arousals used to diagnose milder sleep disordered breathing frequently present in this disorder. HSD is a disorder recently introduced when the Ehlers-Danlos family of genetic connective tissue disorders was reclassified. Patients with HSD often have a narrow and flexible lower airway that frequently leads to mild SDB, causing fatigue and compromise of the quality of their lives. Design/Methods: Ninety-one patients with HSD completed an HST between March 15, 2016 and October 4, 2017. The average REI captured through the HST versus the follow-up PSG, when available, were calculated to compare the sensitivity in patients diagnosed with Hypermobility Spectrum Disorder (M357). Results: Fifty-four patients (59.34%) had inconclusive HST’s. Of those who subsequently had a PSG (11 being lost to follow-up), 21 were diagnosed with OSA (G47.33), 8 were diagnosed with Upper Airway Resistance Syndrome (G47.30), and 14 are still being evaluated. In those with an attended PSG, there was an approximately four-fold increase in sensitivity of the PSG versus the HST. We speculate the reason for this is the unusual flexibility of the lower airway in patients with HSD. Conclusions: Patients with HSD frequently have sleep complaints that need evaluation. Attended PSG’s are necessary to diagnose SDB in patients with HSD, with HST frequently failing to demonstrate sleep disordered breathing in these patients In patients with HSD, HSTs frequently are a waste of time and money, and at best delay diagnosis of sleep disordered breathing. For efficiency and improved patient care, in patients with HSD, attended polysomnography is the diagnostic procedure of choice. Disclosure: Dr. Babcock has nothing to disclose. Dr. Riggs has nothing to disclose. Dr. Rowe has nothing to disclose. Dr. Hunter has nothing to disclose. Dr. O9Shea has nothing to disclose. Dr. Schell has nothing to disclose. Dr. Paul has nothing to disclose. Dr. Varona has nothing to disclose. Dr. Miller has nothing to disclose. Dr. Barnett has nothing to disclose. Dr. Kadia has nothing to disclose.