Seventeen patients with lung transplants were evaluated with inspiratory, postexpiratory, and low-dose, dynamic expiratory thin-section computed tomography (CT). Region of interest measurements were performed on inspiration and expiration images with both techniques, and mean lung attenuation changes between inspiration and expiration images were calculated and compared. Dynamic expiratory thin-section CT resulted in a significantly greater increase in lung attenuation than postexpiratory thin-section CT. Dynamic expiratory thin-section CT may prove useful in the evaluation of patients with lung diseases characterized by air flow obstruction with little increase in patient radiation dose.