Portable Sleep monitoring is a very important method of diagnosis and follow-up for sleep-disordered breathing.  This state-of-the-art issue reviews the most recent information on classification, technical specifications and types of portable monitors, use and limitations of portable monitoring with integration into positive airway pressure treatment. use of portable monitors in children and in patients with oral appliances.  Use of portable monitoring for SDB treatment with upper airway surgery is also discussed.  Current published standards incliding CMS requirements for portable monitoring are reviewed.  Outcome measures, illustrative cases, and a comparison with polysomnogram are included.  Finally, future directions are discussed.