Bronchiolitis obliterans organizing pneumonia (BOOP) is a late complication of hematopoietic stem cell transplantation. Many transplant recipients have returned to their community oncologists before BOOP has occurred. The etiology of BOOP in transplant recipients is not understood fully, but it may be associated with chronic graft-versus-host disease. BOOP presents both vague and common symptoms that can progress into respiratory failure but respond to early and appropriate treatment. Early recognition and treatment of BOOP are essential to improving survival of patients who are post-transplantation. Community oncology nurses are in a key position to support initiation of side-effect management. This article presents information about the etiology, presentation, diagnostic testing, and treatment of BOOP. Two case studies are included that illustrate the typical course of BOOP and its treatment.