We studied nasal mucociliary clearance by means of the saccharin-sky-blue technique in patients with septal deformities of the nose before and after plastic operation. The results were compared with clearance measurements in healthy persons. Prior to operation nasal clearance was statistically significantly slower (p less than 0.05) in the patient group, and mucociliostasis occurred in 21% of all measurements compared with only 3% in the group of healthy persons. 3 months after septoplasty nasal clearance was found normal in all but 3 persons who had an active nasal infection at the time of postoperative investigation. In our opinion the saccharin-sky-blue test serves as a valuable technique in the evaluation of nasal mucociliary function prior and subsequent to operation of patients with septal deformities of the nose.