Background. Niemann–Pick disease type C is a multisystem orphan disease caused by mutations in the NPC1 and NPC2 genes and characterized by clinical polymorphism. The difficulties of managing such patients lie in the diagnosis and differential diagnostic search with other conditions with cholestasis, as well as the initiation of substrate-reducing therapy in young children. Case report. Previously, a case report of Niemann–Pick disease type C, with the manifestation of the disease in infancy and the appointment of off-label pathogenetic therapy was described. The article presents the results of dynamic monitoring of the child on this therapy, its effectiveness and safety. The leading syndromes in the clinical presentation of the disease were cholestasis, cytolysis, hepatosplenomegaly, as well as psychomotor retardation. An extensive differential diagnostic search was conducted with the exception of diseases such as toxic, viral hepatitis, alpha-1-antitrypsin deficiency, autoimmune liver diseases, aminoacidopathy, Alagille syndrome. Genetic testing on the “Cholestasis” panel revealed a mutation in the NPC1 gene. Biochemical diagnostics showed an increase in the concentration of lysosphingomyelin-509 and increased activity of chitotriosidase in dry blood spots. When sequencing the NPC1 gene by Sanger, the nucleotide substitution chr18:21131617G> A in the homozygous state was detected in the child. At 9 months, by the decision of the medical board, the child was prescribed pathogenetic therapy, the effectiveness of which was confirmed by clinical and laboratory relief of cholestasis, positive dynamics of neurological manifestations, in addition, the drug is satisfactorily tolerated by the patient, despite the preservation of an isolated increase in the level of aspartate aminotransferase. Conclusion. The presented case report confirms the need for a thorough differential diagnostic search with the inclusion of a wide range of diseases with the leading cholestasis for the timely detection of infants with Niemann- Pick disease type C, as well as the importance and effectiveness of early administration of pathogenetic therapy.