Ciliary motility in two patients with yellow nail syndrome and recurrent sinopulmonary infections. The yellow nail syndrome (YNS) is described as a combination of yellow nails, chronic lymphedema, pleural effusions, and recurrent sinopulmonary infections, but all these features need not be present for the diagnosis. The mechanism that renders patients with this syndrome susceptible to respiratory infections is not known. To determine whether abnormal ciliary motility is a predisposing factor, in vitro ciliary beat frequency (CBF) was measured in two patients with YNS and recurrent respiratory infections. In each case, the CBF was within normal limits (12 Hz). These data suggest that abnormal ciliary motility is not a pathophysiologic mechanism of recurrent sinopulmonary infections in YNS. 