Purpose: The aim of this study was to evaluate the effects of HMT on protection of lung tissue exposed to HD in the rat. Materials and Methods: In this study twenty Albino Wister adult male rats weighting 200±20 gram were used. Rats divided randomly into 4 groups (each group has 5 rats) as below: Normal saline group (NS), HMT group, HD group (0.25% HD) and HD+HMT group. Normal saline and HD solution were injected by intra tracheal catather. Animals in HMT and HD+HMT groups received HMT by intra peritoneal injection for 14 days daily. All rats were killed after 14 days, a part of lung tissue were removed, fixed and processed for histological evaluation by H&E staining and and apoptotic cell death study by TUNEL kit. In addition, biochemical study (catalase enzyme) was measured in all groups. Results: Histological examination and cell counting data revealed that there were no significant differences between Saline & HMT groups. Alveolar hemorrhage and inflammation, as well as, the number of apoptotic cells in the HD group was significantly increased when compared to HD+HMT group. Conclusion: HMT have prophylactic & therapeutics effects in the lung tissue against HD.

Keywords: Sulfur Mustard, Lung Tissue, Hexamethylenetetramine