Cadmium is a toxic, heavy industrial metal that causes serious environmental health hazards. Cadmium containing compounds have been classified as known human carcinogens and epidemiological data show causal associations to different types of cancers. This study designed to assess the carcinogenic effects of Cadmium on the gingival tissue of rats. Material and methods; Sixteen male albino Rats (age: 8 to 10 weeks and about 150 to 180 g body weight) from Animal Center of Faculty of Medicine, Mansoura University. The animals were divided into two equal groups, group I (control) and group II (cadmium chloride) rats were given 2 ml dose of a solution containing 10 mg/kg body weight of monohydrated cadmium chloride orally by gavage needle for 24 days. By the end of experiments, gingival epithelium around the teeth were carefully dissected, processed and stained using Haematoxyline & Eosin and immunohistochemical evaluation by iNOS. Statistical analysis was done to observe the statistical significant differences between the Cd group and control group in relation to dysplastic changes and iNOS immunoreaction. Results: the gingival tissue of Cd group revealed several dysplastic changes as, drop shape rete pegs, loss of polarity of basal cells, nuclear hyperchromatism, pleomorphism and increased mitotic pattern. a statistical significant difference regarding iNOS immunoreaction was found between control group and Cd group. conclusion to this study Cadmium chloride at low concentration and longtime of exposure can cause dysplastic changes in gingival tissue of rats.