Mucociliary clearance from the respiratory tract depends on normal function and structure of cilia lining the mucosa along the nasal cavity and from the larynx to the sixteenth division of the bronchial tree. Cilia transport mucus from the bronchi to the hypopharynx and from the anterior nasal cavity to the oropharynx utilizing a synchronized beating motion. Mucus is propelled from the anterior nasal cavity at 4 to 7 mm/minute and from the depth of the bronchial tree at 4 to 5 mm/minute. Most debris and mucus are cleared from the ciliated airways in 6 to 24 hours. Disruption in ciliary motility caused by alterations in function or structure leads to ineffective mucociliary clearance, which, in turn, may result in sinusitis, otitis media, bronchiectasis, and sinopulmonary infections. As early as 1901, an association among sinusitis, bronchiectasis, and dextrocardia was noted. This triad was described more completely in the 1930s as chronic sinusitis, bronchiectasis, and situs inversus and became known as Kartagener syndrome (KS). In the late 1950s, infertility in men with this triad also was discovered, but not until the mid 1970s did ultrastructural examination reveal ciliary abnormalities. Immotile cilia syndrome became the accepted term for this condition. Later, researchers noted that many of those patients with KS and those with mucociliary clearance abnormalities alone (chronic sinusitis and bronchiectasis) had aberrant ciliary motility and ineffective mucociliary clearance. This finding led to the implementation of the current term, primary ciliary dyskinesia (PCD).