We present the results of 7-year follow-up of a patient with primary immunodeficiency, such as severe combined immune deficiency, X-linked variant. The child has been ill from 11 month of age. He was taken to the Regional Infectious Disease Hospital in Irkutsk by sanitary aviation in extremely serious condition, which threatened his life. At 1 year 2 months he was transferred to Irkutsk State Regional Children’s Clinical Hospital due to deterioration of the general condition, prolonged fever, expressed by hypoxemia. At 1 year 3 months he was diagnosed with primary immunodeficiency, X-linked severe combined immune deficiency, persistent CMV infection in the department of clinical immunology of the Republican Children’s Clinical Hospital in Moscow. The diagnosis was confirmed by molecular genetic method (mutation с.664С˃Т was detected in exon 5 of the IL2RG gene in the hemizygotic state). At 1 year 9 months, haploidentical transplantation of hematopoietic stem cells from the father was performed. According to the chimerism, immune transplant rejection was observed after 1.5 months. At 2 years 11 months, the boy successfully underwent allogeneic bone marrow transplantation from an unrelated donor in the Children’s Oncology and Hematology Hospital of the University Hospital Freiburg (Germany). The child is being regularly observed in Irkutsk State Regional Children’s Clinical Hospital. He suffers from respiratory infections 4–5 times a year in a mild form. He corresponds to peers in physical and psychomotor development.