Juvenile idiopathic arthritis (JIA) is one of the most severe forms of chronic pathology in children. The high frequency of JIA compared with other diffuse diseases of the connective tissue, the tendency to early disability and the possibility of systemic manifestations involving the internal organs in the pathological process dictate the need for timely diagnosis of complications and the selection of adequate therapy. One of the vulnerable organs in patients with JIA is the liver. The reason is autoimmune processes on the one hand and the effect of drugs on the other.