Obliterative bronchiolitis (OB) is a form of chronic rejection after lung transplantation. Lentiviral vectors (LVs) facilitate long-term gene transduction in many tissues and organs. We hypothesized that lentiviral gene transfer of interleukin (IL)-10, a potent immune-modulating cytokine, to the lung could modulate the alloimmune responses in the lung after transplantation. C57BL6 mice received LVs encoding luciferase, enhanced green fluorescent protein (eGFP), or human IL-10 (huIL-10) through airways and underwent repeated bioluminescent imaging, immunofluorescence imaging, or ELISA of lung tissues, respectively. Luciferase activities peaked at day 7 and were stable after day 28 to over 15 months. eGFP staining demonstrated LV-mediated gene transduction mainly in alveolar macrophages. LV-huIL-10 delivery resulted in stable long-term expression of huIL-10 in the lung tissue (average 3.66 pg/mg at 1 year). Intrapulmonary allograft tracheal transplantation (BALBc→C57BL6) was used as a model of OB. LV-huIL-10 or LV-eGFP were delivered 7 days before transplantation and compared with no LV-transfection group. Allograft airways at day 28 were almost completely obliterated in all the groups. However, at day 42, allograft airways treated with LV-huIL-10 showed a spectrum of attenuation in airway fibrosis ranging from complete obliteration through bubble-like partial opening to complete patency with epithelial coverage in association with a significantly reduced obliteration ratio compared with the other groups (p<0.05). In conclusion, lentivirus-mediated gene transduction is useful in achieving long-term transgene expression in the lung. Long-term IL-10 expression has the potential to attenuate allograft airway obliteration. LV-mediated gene therapy could be a useful strategy to prevent or treat OB after lung transplantation.