Bronchiectasis, or abnormal dilation of the airways, is a condition typically characterized by chronic and recurring respiratory tract infections. Frequently, depending on the underlying cause, these infections involve the entire respiratory tract resulting in sinus, ear, and lung disease. This condition used to be more common in children prior to immunizations for childhood infections. It continues to be a significant problem in developing countries and in specific groups of individuals in the U.S. Cystic fibrosis (CF) is the most commonly associated genetic condition and tremendous strides have been made in recent years in understanding the mechanisms of this disease that are leading to a multitude of emerging novel treatment strategies. The mechanisms of other causes for bronchiectasis have not evolved to this degree, and many of the disease-specific treatments being assessed for cystic fibrosis may not be effective for non-CF bronchiectasis. Often bronchiectasis can be associated with chronic infections from environmental germs such as the nontuberculous mycobacteria.