The Swyer-James syndrome (unilateral hyperlucent lung) is a condition which likely has its origin during childhood. Although many of these children are asymptomatic, symptoms of chronic and repeated infections, decreased exercise tolerance, arterial blood desaturation, and hemoptysis may arise. The initial diagnosis is often made roentgenographically, whereupon the typical finding is a small, hyperlucent, devascularized lung (or portion thereof) which shows little change in volume during the respiratory cycle. It is important for the pediatrician to be aware of this condition because it often originates and is first seen in the pediatric age group. The changes can be progressive, and although treatment is usually conservative, surgery might be indicated in some selected cases where medical management alone is not sufficient.