The clinical spectrum of the scimitar syndrome ranges from severely ill infants to asymptomatic adults. The true incidence of the disorder is unknown because the syndrome may remain undetected in asymptomatic patients until a chest roentgenogram is obtained. We have presented the contrasting clinical experiences of two adult women, one with few symptoms and a benign course, and the other with exacerbation of her asthma from recurrent upper respiratory tract infections originating in the lower lobe of her right lung. Improvement resulted from surgical resection of this congenitally abnormal, bronchiectatic segment of lung.