Symptoms of multiple myeloma (MM) include bone destruction with pathological fractures, kidney failure and frequent infections, which are the major causes of patient mortality. In our recent research, we demonstrated that the degree of dendritic cell (DC) subpopulation deficit could be related to MM progression, which in consequence may contribute to the MM-related impairment of the immune responses. In the present study, we determined by flow cytometry the frequencies of CD4+ and CD8+ T cells, NK, and NKT-like cells as well as their correlation with myeloid and lymphoid populations of DCs in patients with MM. The study involved 50 patients diagnosed with MM at the Department of Hematology in the Holycross Cancer Center in Kielce. The research samples were collected after the MM diagnosis and before the initiation of anticancer therapy. The obtained results revealed the relations between the percentages of DC subpopulations and lymphocyte subsets, especially the activated ones, in the peripheral blood (PB) and bone marrow (BM). The described role of DCs in the process of the immunological response, either adaptive or innate, leads us to conclude that the decrease of the number or percentage of these cells may have a negative impact on the process of activation of effector cells and, consequently, on the effectiveness of a response to foreign as well as neoplastic antigens in patients with MM.