In this issue of Clinics in Chest Medicine, guest editors Drs. Cormac McCarthy and Nishant Gupta bring their considerable expertise to the topic of Rare and Orphan Lung Diseases. Top experts discuss both rare and orphan diseases (those which are not widely researched, those where specific treatments are not available, and those which may only be of limited interest to scientists and doctors). Topics in this issue include primary ciliary dyskinesia, multiple cystic lung diseases, and idiopathic eosinophilic pneumonias.