This current study was conducted to evaluate the ability of Nano-selenium (Nano Se) in inhibition of aflatoxin B1 toxicity on gingiva and periodontal ligament of rats through histological investigation and immunohistochemical detection of TNF-α & caspase-3 expression in gingiva and desmin expression in the periodontal ligament. Material and Methods: Forty adult male albino rats were divided into 4 equal groups: Group I served as control rats (normal), Group II (aflatoxin B1 group) received aflatoxin B1 (250 μg/kg b.w/day) orally by gastric tube 5 days/week for 4 weeks, Group III (AFB1and Nano-Se group) received aflatoxin B1 (250 μg/kg b.w./day) and 100 mg /animal of Nano-Se orally for 5 days/week 4 weeks. Group IV (Nano-Se group) received 100 mg /animal of Nano-Se orally for 5 days/week through gastric tube. At the end of the experiment, the upper and lower jaws were dissected out after scarification under general anesthesia. Gingival and jaw samples were collected and processed for histological techniques. Immunohistochemical estimation of TNF-α as pro-inflammatory mediator, caspase-3 to determine any apoptotic cells and desmin for detection of collagen fibers was performed