This study was purposed to detect the serum concentrations of interleukin-17 (IL-17) in patients with multiple myeloma (MM), and to investigate its clinical significance. the serum IL-17 levels in 33 patients with MM and 20 normal control subjects were quantified by using double antibody sandwich ELISA, and serum β2-microglobulin (β2-MG) levels were detected by radioimmunoassay. The results showed that the serum concentrations of IL-17 and β2-MG in patients with MM were significantly higher than those in the control group (P < 0.001), the serum concentrations of IL-17 and β2-MG in active stage were significantly higher than those in stable stage (P < 0.05), the serum concentrations of IL-17 and β2-MG were significantly higher in stage III than that in stage II according to International Staging System (ISS) (P < 0.05), the serum IL-17 and β2-MG levels were significantly correlated (r = 0.690, P < 0.05). It is concluded that the serum IL-17 level correlates with active/stable stages of MM and staging of MM, IL-17 may play an important role in development stage and prognosis of this disease.