question: The review outlines current views on immune system in multiple myeloma (MM) and the basic pathogens inducing infectious complications in such patients. Although in recent years there has been considerable progress in studying molecular mechanisms of the MM development (pathogenesis), methods of its diagnosis, treatment, and prediction of outcomes, one of the main causes of death within this group of patients is infectious complications. In this context, it would be relevant to further study immune disorders and the spectrum of infectious pathogens common in the MM patient cohort. The study and correction of immunological status can contribute to improving the MM outcomes, which in turn will lead to increased life expectancy. © 2021 Practical Medicine Publishing House. All rights reserved.