Interest in the problem of bronchiectasis has been particularly enhanced by the recent advances in thoracic surgery. The abundant literature comprises extensive clinical reviews1-3 as well as experimental investigations.4-7 The cause of bronchiectasis and the relationship of this condition to chronic sinusitis have been intensively discussed. For present purposes, however, detailed penetration of these questions is superfluous. We would only point out that changes in the ciliary activity and in the mucus secreted in the respiratory tract have been suggested as possible factors in the development of bronchiectasis and atelectasis.6,7 Our investigations were intended to provide an orientating conception as regards ciliary activity in bronchiectasis and chronic sinusitis. We therefore measured the rate of ciliary beat on sinus mucosa and bronchial mucosa excised from persons with chronic sinusitis and/or bronchiectasis. For comparison, we also measured ciliary beating on specimens of mucosa from the same sites in persons