In recent years, monitoring the amount of pollutants in aquatic ecosystems by quantity measures in water, sediment and fish tissue has shifted to the quality measures of pollutant effects on aquatic animals and assessment of aquatic animal health and, ultimately, the ecosystem. This research performed on three replicates has examined the histopathological response of hepatopancreas and gill in Metopograpsus messor crab exposed to cadmium pollutants. We prepared an aquarium that contained a 5 μg/L concentration of cadmium as well as a control group. After the start of the experiment, we sampled the crabs in 2 steps short-time (72 h) and long-time (14 days). After the routine histological procedures, we performed H & E staining. Oserved complications in the gills included: disruption of the pillar cells and collapsed lamellae, hyperplasia, necrosis, detached cuticle, club-shaped distal tips of gill lamellae, vacuolisation, malformation at the tip of the gills, slight lamellae distortion. In the hepatopancreas we observed formation of abnormal lumen, necrosis, thickened basal laminae, increased numbers of B-cells, presence of reserve inclusion, and dilation of the hemal sinuses. A comparison of the two groups showed a direct correlation between the duration and severity of damage.