Objective/Hypothesis: Physiologic saline (NaCl 0.9%) is commonly used in treating acute and chronic rhinosinusitis. Moreover, physiologic saline is used as a control medium, vehicle, or solvent in studies on ciliary beat frequency (CBF). Hypertonic saline (NaCl 7% and 14.4%) has been applied in attempts to enhance mucociliary transport in patients with cystic fibrosis or asthma and in healthy subjects. Therefore the objective of this study is to document in vitro effects of saline solutions in different concentrations on CBF. Study Design: Experimental, in vitro. Methods: The effects on CBF of cryopreserved mucosa of the sphenoidal sinus was measured by a photoelectrical method. Initial frequencies, measured in Locke-Ringer's solution (LR), were compared with CBF after exposure to NaCl in concentrations of 0.9%, 7.0%, and 14.4% (w/v), Results: NaCl 0.9% has a moderately negative effect on CBF, The 7% solution leads to a complete ciliostasis within 5 minutes, although this effect turns out to be reversible after rinsing with LR, A hypertonic solution of 14.4% has an irreversible ciliostatic effect. Conclusion: LR is an isotonic solution that has no effect on CBF. Therefore it is probable that this solution is more appropriate than saline for nasal irrigation and nebulization or antral lavage, Moreover, the results of this study suggest that mucolytic effects induced by hyperosmolarity should be attained preferably with hypertonic saline 7% in patients with cystic fibrosis or asthma. At this concentration, the ciliostatic effect is reversible, whereas irreversible changes are to be expected at higher concentrations.