Systemic onset juvenile arthritis is the complex autoinflammatory disease with multigenic type of inheritance. It is characterized by significant systemic manifestations and unfavourable adverse events, among which macrophage activation syndrome and pulmonary involvement are playing crucial role. This article presents data on the frequency and features of the disease course, possible development predictors and clinical-radiological picture of pulmonary involvement in systemic onset juvenile arthritis. Possible factors (including hereditary) affecting the process of pulmonary involvement development and the role of genetically engineered biologic therapy are considered.