&NA;Lung transplantation is now considered to be a therapeutic option for patients with end‐stage lung diseases. Unfortunately, because of the problems of lung allograft rejection, it is only a treatment and not a cure. Critical to the continuum of acute to chronic (bronchiolitis obliterans syndrome) lung allograft rejection is persistent allorecognition with T‐cell activation by costimulatory molecules leading to the expression of cytokines, chemokines, and growth factors. These events establish a persistent recruitment of peri‐airway/vascular alloreactive leukocytes that eventually cause an aberrant reparative process. The aberrant repair process involves the recruitment and proliferation of leukocytes and mesenchymal cells, ultimately resulting in lung dysfunction in the form of fibro‐obliteration. Studies involving patients with bronchiolitis obliterans syndrome and translational studies using animal models have demonstrated the expression of cytokines, chemokines, and growth factors all play specific roles in pathogenesis of bronchiolitis obliterans syndrome. In this review, we will discuss the role of cytokines in mediating the pathogenesis of bronchiolitis obliterans syndrome.