In the work presented in this issue, Goto and colleagues (1) have provided strong new evidence that a distinct population of lymphocytes resides within the bronchial epithelium. By following the fates of human bronchial xenografts after transplantation into SCID mice, these investigators were able to show long-term persistence (over 5 mo) of human intraepithelial lymphocytes (IEL) in grafts, even as the number of lymphocytes in the adjacent lamina propria declined precipitously. Although little is known about the function of bronchial IEL, their location suggests important roles in the control of immune and inflammatory reactions in the lung. Goto and coworkers’ work should prompt further investigation into the roles of bronchial IEL in health and disease.