This study was to investigate the differences of inflammatory reaction and oxidative stress due to sulfur mustard (SM)-induced acute pulmonary injury via two ways in rats. In intraperitoneal and tracheal SM groups, injected intraperitoneally and instilled intratracheally with 0.1mL diluted SM (0.96 LD 50 =8mg/kg) and SM (0.98 LD 50 =2mg/kg) were administered in rats. In bronchoalveolar lavage fluid, serum, and alveolar septum, lactate dehydrogenase, glutathione peroxidase, tumor necrosis factor-α, interleukin-1β, interleukin-6, C-reactive protein, intercellular adhesion molecule-1, vascular cell adhesion molecule-1, l-selectin, r-glutamyl transpeptidase, thiobarbituric acid reactive substances levels as well as the expression of CD4, CD20, CD68, 8-hydroxy deoxyguanosine, nuclear factor-E2-related factor 2, and heme oxygenase-1 measured by ELISA, immune scatter turbidimetry and immunohistochemical method in the intraperitoneal SM group were increased at each time-point compared with the tracheal SM groups, respectively. These data demonstrated an increased inflammatory reaction and oxidative stress indices in rat via intraperitoneal injection under similar SM LD 50 doses., (Copyright © 2017 Elsevier B.V. All rights reserved.)