Endoplasmic reticulum stress(ERS)is a subcellular pathological state formed by imbalance of environment in endoplasmic reticulum,and is regarded as an important pathway that mediates apoptosis.Recent studies have found that after ERS occurs in various immune tissues and cells,immunosuppressive effect that produced is involved in regulating body's immune homeo-stasis,affecting occurrence,outcome and prognosis of many diseases.This article reviews production of ERS,signal regulation and pathophysiological changes in immune organs and immune cells,and its role in development of inflammatory diseases and tumors.