Author studied the pathogenesis of Sino-bronchiectasis with review of clincal and pathological findings of resected lungs in 24 eases of bronchiectasis,and the results were as follows: 1. Of the 24 eases of bronchiectasis, Sino-bronchiectasis were found in 11 cases and these cases most commonly, developed in first and second decade of life. In a majority of these cases,the main symptoms were the signs of wet bronchiectasis. 2. The typical roentgenograrn changes of plain chest x rays were increase in size and loss of definition of the markings and bronchographically revealed the cylindrical or tubular form in major-ity of these cases. 3. Pathologically Sino-bronchiectasis involved specific segmental areas of the lungs such as left basal and S4+5 segments and revealed commonly tubular dilatation. The most common findings of bronchial wall of dilated bronchus were the inflammatory cellular infiltration and cylindrical hyperplasia of mucus epithelial layers. 4. It was suspected that there were some causal relations in pathogenesis between chronic sinusitis and bronchiectasis.[KTCS 1973;2:151-158]