The article deals with severe hereditary disease - hepatolenticular degeneration (Wilson - Konovalov disease). Hepatolenticular degeneration is a monogenic autosomal recessive genetic disorder. Pathogenetically, it is a genetic disorder of copper metabolism when copper accumulates in excessive amounts in target organs, primarily in the liver. More commonly it manifests atyoung age and, when untreated, progresses rapidly to death. At the same time, hepatolenticular degeneration is one of a few of hereditary disease for which an effective pathogenetic therapy with copper-eliminating medications has been developed to reduce the amount of dietary copper and to remove its excess from the body. The risk factors of unfavourable type of decease development are: the severity of clinical aspects at the time of diagnostics in neurological stage, period of the delay of the copper-eliminate therapy prescription and the degree of mind disorder. The prognostication on hepatolenticular degeneration depends on the duration of the decease, time of the therapy beginning and the compliance to it. We report about two clinical observations of hepatolenticular degeneration, demonstrating the necessity to use the full complex of clinical-laboratorial and instrumental analysis in all cases of developing motor extrapyramidal defects, combined with psychiatric disorders and pathology of internal organs. This work proved that it is necessary to evaluate all symptoms in the dynamics of disease course and that symptoms signaling about pathology of copper metabolism should not be ignored, and paying attention only to some of the indicants is not advised.