Nasal mucociliary clearance is the first line of defense of the ciliated epithelium of the respiratory tract against inhaled particles, Several rhinopathic conditions involve alterations in nasal mucociliary clearance. The purpose of this study was to assess the clinical role of rhinoscintigraphy in evaluation of nasal mucociliary clearance function in allergic rhinitis patients and in sinusitis patients and healthy controls for comparison. A technetium 99m-labeled macroaggregated albumin (Tc-99m MAA) drop was deposited on the floor of the nasal meatus about 1 cm behind the mucocutaneous junction, and its course was followed with a gamma camera, The nasal mucociliary clearance function was measured as the velocity of the nasal mucociliary transport of the Tc-99m MAA droplet. The mean velocity of nasal mucociliary transport in the allergic rhinitis patients was 2.71 +/- 0.76 mm/min (2,65 0.76 min/min in the right nostril; 2.77 +/- 0.76 mm/min in the left nostril). The mean velocity of nasal mucociliary transport in the sinusitis patients was 1.80 +/- 0.64 mm/min (1.79 0.65 mm/min in the right nostril; 1.82 +/- 0.63 mm/min in the left nostril). The mean velocity of nasal mucociliary transport in the 25 healthy controls was 4.28 +/- 1.38 min/min (4.30 +/- 1.35 mm/min in the right nostril; 4.27 +/- 1.42 mm/ min in the left nostril). A significant difference in nasal mucociliary clearance was observed among the 3 groups. We suggest that Tc-99m MAA rhinoscintigraphy may be a useful noninvasive tool to evaluate the nasal mucociliary clearance function in allergic rhinitis patients.