The authors make a brief synthesis of the present data on the penetration and retention of therapeutical aerosols in upper airways. They analyze the mechanisms involved during the penetration of aerosols in the regions of the upper airways which are not swept by the inspiratory airflow, particularly in the accessory cavities of nasal fossa, sinus and Eustachian tube. Experimental results reveal that diffusion of aerosols can be improved at this level either by sound vibrations, or by combining vibrations to intermittent overpressures.