Eighteen children (8 boys, 10 girls) aged 6-16 years were examined. In all of them the basic diagnosis was bronchiectasia. Catheterization of the lesser circulation global spirometric examination, and perfusion lung scintigraphy with 99mTc both before and 2--4 years after lung resection were performed. Operations performed: 14 cases of lobectomy, one of bilobectomy, three of pneumonectomy. In all of the 14 children after lobectomy the pulmonary arterial pressure remained normal even during exercise. In contrast to this, in the three children after pneumonectomy and in the one boy after bilobectomy the mean pulmonary arterial pressure exceeded 20 mmHg at rest or after exercise. The total pulmonary resistance, converted per square metre of body surface, was--with a single exception [4.7 units before surgery]--within normal limits; after minor resections it rather tended to decrease, whereas in two of four children after major resections it slightly increased. Postoperative perfusion lung scintigram revealed a worsening in comparison with the preoperative finding in practically all of the children. This worsening can be ascribed not only to the restriction of lung tissue, but also to a compensatory emphysema of the remaining parenchyma. In patients with bronchiectasia, extensive resections have uncertain long-term prognosis.