Клинико Clinical and Immunological Features of Infectious Complications in Patients with Multiple Myeloma Background: Infectious complications -the leading cause of mortality in patients with multiple myeloma (MM), their appearance is regarded as an adverse prognostic factor in the course of the disease. Objective: The aim of our study was to evaluate the clinical and immunological features of infectious complications in patients with G-immunochemical MM to find the most informative indicators in their forecasting. Methods: A randomized controlled trial was made. All patients were divided into 3 groups for comparison: Group 1 (n =47) -MM patients, G-immunochemical variant with infection, Group 2 (n =54) -MM patients, G-immunochemical option no infectious complications, and Group 3 (n =125) -healthy volunteers. Research material was deoxygenated blood taken on admission of a patient to the hematology department before the pathogenetic treatment. Identification of G-variant was carried by immunofixation and electrophoresis. The immune status was assessed by indirect immunofluorescence. The concentration of IgA, M, E and G, and the levels of IL 2, IL 4, IL 8, TNF α, IFN γ