Interest in surgical therapy for emphysema has grown phenomenally since the reintroduction of lung volume reduction surgery (LVRS). Although early results have shown promise, important controversies have also emerged. Some of the central issues include refining patient selection criteria, identifying optimal measure ments of improvement after LVRS, achieving a more complete understanding of the functional consequences after LVRS, and, most importantly, identifying the effect of LVRS, an admittedly palliative procedure, on disease progression and mortality in emphysema. Secondary issues surrounding LVRS include its role in combination with other procedures and its potentially large eco nomic impact. The National Emphysema Treatment Trial, a joint effort between the National Heart, Lung, and Blood Institute and the Health Care Financing Administration, is designed to address and clarify these and other questions about LVRS.