Pathological experiments should be considered following oral administration of ZnO. Effect of different doses of ZnO nanoparticle on LDH in oral method showed significant differences in control group (p<0.05) at high dose. Levels of IgG, TNF-α and IL-6 also elevated after administration of ZnO. The level of GSH decreased significantly. Lung damages included hyperemia and bleeding, atelectasis, light emphysema, pribronchiolitis, perivasculitis of lymphocyte in intensive level, pneumonia and increased secretion of exudates into bronchial. There was a significant difference in perivasculitis and pribronchiolitis among different doses of ZnO as compared with the control group (p<0.05). The result of this study showed that increasing doses of nanoparticles could cause significant damages to the lung tissue and to increase LDH, IgG, TNF-α and IL-6 and emphasizes that exposure to high concentration of ZnO could cause irreversible damages to different organs including lung and threaten the human health. This finding could be important as a health hazard to those who are in continuous exposure to ZnO nanoparticles.