Objective： To study the expression and role of IL-6, IL-6 receptor(IL-6R) and acute phase reaction factor (APRF) in PMNC of multiple myeloma(MM) patients. Methods:The bioactivity of IL-6 and the level of sIL-6R in sera of MM patients were measured using IL-6 dependent cell line 7TD1 and ELISA respectively. The APRF activity of PMNC DNA binding protein was observed by gel blocking electrophoresis (EMSA). Results:The bioactivity of IL-6 and the level of sIL-6R in MM sera were significantly higher than those of the control and the level was coordinated with that of the tumor. The results of PMNC DNA binding protein EMSA showed that PMNC of MM patients expressed APRF after stimulation of IL-6,whereas there was no activity of APRF in the normal PMNC. Conclusion:In MM,some regulation machines of IL-6 signal transduction pathways changed (eg.protein kinase), resulting in the activation of transcription of acute phase reaction element(APRE), APRF may have a role in pathogenesis of MM.