Nesosteine, which is active on airway secretions, has been studied by assessment of the mucociliary clearance of the frog palate. Sputum was collected from patients admitted to hospital with acute exacerbations of chronic bronchitis with mucous expectoration. The relative speed of transport was measured for each patient before and after oral administration of 600 mg/day nesosteine. A significant increase in the mucus transport rate was found at the end of treatment.