ObjectivetTo investigate the interleukin-16 (IL-16) mRNA expression and IL-16 secretion by peripheral blood mononucle-ar cells (PBMCs) of patients with lupus nephritis (LN) .Methods: 15 patients with active LN, 10 with inactive LN and 8 normal controls were included in the research. TTie supernatant IL-16 levels of freshly isolated PBMCs were measured by ELISA; the IL-16mRNA level were measured by RT-PCR.Results: As compared with the control group, both active and inactive LN patients had significantly increase in IL-16mRNA expression and IL-16 secretion, but didn't find the difference of IL-16mRNA expression between active and inactive LN groups.Conclusion: LN patients can endogeneous over-express IL-16 gene and abnormally produce IL-16 protein by PBMCs . IL-16 might play a role in the patho-genesis of LN.