The intensive addition of nitrogenous fertilizers to soil leads to the accumulation of soil nitrate that in turn affects soil fauna. The hepatopancreas is the major metabolic organ in crustaceans. It has an important function in the assimilation of nutrients and structurally includes two types of cells (B and S). This study was designed to investigate the negative effects of nitrate on the hepatopancreas of the terrestrial isopod Porcellio laevis. The isopod was subjected to different concentrations; 30, 60 and 90 ppm of NaNO3 in food diet to study the histopathological changes on the hepatopancreas. The study revealed that the hepatopancreatic epithelium of the exposed isopod displayed numerous pathological changes varied from destruction of the apical cell membrane with the appearance of deeply stained cytoplasm to complete disintegration of B cells especially in 90 ppm treated group. A trend toward histochemical changes of protein, neutral mucopolysaccharides, acidic and sulphated mucopolysaccharides in hepatopancreatic epithelium were observed. Quantifying these changes in the hepatopancreas were assessed, using image analysis, it indicated the presence of dose-related changes in the area of hepatopancreatic cells, nuclei and lumen. It could be concluded that the recovery process in P. laevis from nitrate toxicity is a slow one.