Some epidemiological and clinical-etiological studies are reported about the incidence of lingua nigra villosa (black hairy tongue) among 3334 children aged from 2 months to 14. It has been very convincingly established that the disease occurred in children administered antibiotics for the treatment of a primary disease. Some new data are presented about the clinical pathology of glossitis on the base of clinical, paraclinical, microbiological and virological studies and reliable possibilities of affecting by nistatin-prednisolone emulsion (NAP).