A master's thesis at the faculty of the college of science at the University of Basrah (Molecular genetic study of microbiota isolated from human tongue), and showed the researcher's thesis (Heba Mohammed Mousa) Supervised by Prof. Dr. Munaff J. Abd Al-Abbas. Thesis aims to isolation and identification microbiota from tongue of infants and compare them with bacteria from tongue of children with normal feeding, in addition to isolation and identification of microbiota from tongue of diabetic patients and compare them with healthy people and concluded Klebsiella pneumoniae is the predominant species in tongue of infants, in addition to the emergence of pathogenic bacterial species on the dorsal of tongue of diabetic patients were shown, making these categories are at risk of developing of many diseases, including mouth diseases, pulmonary infections and diarrhea for being immunocompromsid patients. The inhibitory and lethal effect of mouth washing ( Listerine ) were studies in addition to mutagenic effect In vitro and In vivo. The presence of Sea gene (encoding for enterotoxin) was also studies on bacterial species isolated from human tongue making them at risk of abdominal infections. And recommended ( the nessecity to reduce the bacterial load on tongue, in addition to using Listerine washing for hospitalized patients especially the elderly, do not neglect ulcers and wounds in the mouth, glycemic control for diabetic patients, more studies on enterotoxins produced by tongue microbiota and investigation of the relationship between the role of tongue microbiota and infections in other body systems.