Plasma cell neoplasms (PCN) are monoclonal proliferations of plasma cells that produce a clonal paraprotein. Various cytokines are involved in the immune response and inflammatory processes in plasma cell neoplasms. To determine the levels of selected cytokines in the blood serum of patients with plasma cell neoplasms and to study their role in progression. The study was conducted from October 2018 to January 2022. Republican Research Center for Radiation Medicine and Human Ecology Gomel, Belarus Patients: 210 PCN patients (median monoclonal gammopathy of undetermined significance (MGUS), n=90; multiple melanoma (MM), n=101; solitary plasmacytoma (SP), n=19). The median MGUS age was 61.0 (54.0 and 67.0), MM-65.0 (58.0 and 70.0), SP-61.0 (54.0 and 68.0). Cytokines (IL1, IL2, IL6, IL8 and TNF-α) were determined. Studied cytokines are associated with the process activity in PCN. The levels of IL2 (p=0.001), IL6 (p=0.006) and TNF-α (p=0.006) with the progression of MM in comparison with MGUS and SP. An excess of IL8 levels was found in patients with MM with bone and kidney damage, in MGUS patients with progression (p = 0.014). An excess of the IL6 level (p=0.00001) was revealed in MM patients at the stages of ISSII and ISSIII and with high levels of LDH (p=0.0088), anemic syndrome (p=0.0064) and hypercalcemia (p=0.021). We have revealed a significant excess of the levels of IL1 (p=0.0036), IL2 (p=0.069) and TNF-α (p=0.043) in MM patients of a high-risk group (κ/λ <0.1 and >10), in comparison with the group with the absence of this criterion. A correlation was revealed in MM patients by levels of IL1 (p=0.02), IL6 (p=0.00001), IL8 (p=0.02) and TNF-α (p=0.004), IL6 (p=0.0004), IL8 (p=0.015) and TNF-α (0.006), in SP patients by IL6 level (p=0.05). The progression of diseases is characterized by an increase in the levels of various cytokines, depending on the signs of organ damage: in MM it was reflected by IL2, IL6, and TNF-α, in MGUS by IL1, and IL6, and in SP by IL1. When detecting lytic lesions and kidney damage, we have revealed a correlation with the level of IL8 and TNF-α.