Abstract: OBJECTIVE To explore the expression of Toll-like receptor 4（TLR4）/myeloid differentiation factor（MyD88）/nuclear transcription factor-κB p65（NF-κB p65） signaling pathway in peripheral blood mononuclear cells of patients with septic shock. METHODS A total of 112 patients with septic shock who were treated in The Third People’s Hospital of Henan Province from Jan 2019 to Mar 2021 were assigned as the case group, meanwhile, 56 patients who did not have septic shock were chosen as the control group. The expression levels of TLR4, MyD88 and NF-κB p65 proteins as well as the levels of tumor necrosis factor-α（TNF-α）, interleukin-6（IL-6） and monocyte chemoattractant protein-1（MCP-1） were compared between the two groups of patients, and receiver operating characteristic（ROC） curve analysis was performed for the value of TLR4, MyD88, NF-κB p65 protein and serum inflammatory factors in diagnosis of septic shock. RESULTS The levels of serum inflammatory factors TNF-α, IL-6 and MCP-1 of the case group were significantly higher than those of the control group（P＜0.05）. The expression levels of peripheral blood monocytes TLR4, MyD88 and NF-κB p65 proteins of the case group were significantly higher than those of the control group（P＜0.05）. The sensitivities of TLR4, MyD88 and NF-κB p65 proteins were respectively 89.29%, 68.75% and 74.11% in diagnosis of septic shock, the specificities were respectively 55.36%, 66.07% and 67.86%. The sensitivities of the serum inflammatory factors TNF-α, IL-6 and MCP-1 were respectively 67.86%, 71.43% and 75.00% in diagnosis of septic shock, and the specificities were respectively 60.71%, 91.07% and 85.71%. CONCLUSION The molecular pathological mechanism of septic shock may be associated with up-regulation of TLR4/MyD88/NF-κB p65 signaling pathway and enhancement of inflammatory response.