The 2018 international consensus defines bruxism as repetitive jaw muscle activity characterized by teeth clenching, grinding, and/or jaw stiffening or protrusion. The incidence of bruxism in children varies between 3.5 - 47.6%. As in the adult population, there are two types of bruxism in the developmental age: sleep bruxism and awake bruxism. The division based on etiology divides bruxism into primary and secondary. The causes of bruxism in children are still unclear. Among the factors predisposing to the occurrence of this phenomenon, there are psychological, environmental, genetic and systemic causes, and the greatest impact on the appearance of bruxism are: stress, anxiety disorders and sleep disorders. Diagnosis of bruxism is based on an interview, clinical examination and instrumental tests of masticatory muscle activity, i.e. electromyography, which is one of the components of polysomnography. Therapeutic treatment should focus on finding the causes of increased masticatory muscle activity and their treatment. Cooperation of dentists with doctors of other specialties and psychologists is necessary. The phenomenon of bruxism in children requires the management of etiology, methods of diagnosis and treatment.