In a retrospective study, the authors evaluated the initial and follow-up radiographs and ventilation perfusion (V/Q) scans of 12 boys and girls with lobar emphysema who were treated conservatively and were followed up for a median of 3 years (range, 6 months to 12 years). All 12 boys and girls underwent anteroposterior and lateral chest radiography at admission and at varying intervals thereafter. Ten patients underwent V/Q lung scanning; six of these procedures were performed within 4 weeks of initial radiography. Six patients underwent follow-up V/Q scanning. Thoracic computed tomography was performed in four patients at admission. In all 12 cases gradual improvement in symptoms was paralleled by improvements in serial chest radiographs and, in six cases, by improvements in V/Q scans. The affected lobe appeared to be less hyperinflated on follow-up radiographs. For those children who showed functional improvement, ventilation improved more than perfusion, as demonstrated on the V/Q scans. At initial radiography the adjacent "collapsed" lobe was seen to function well, suggesting that it was only compressed.