Objective To study the clinical significance and changes of serum TNF-α、IL-6、IL-8、PAFand AGT-Ⅱ in patients with severe acute pancreatitis(SAP). Methods Serum TNF-α、IL-6、IL-8、PAF、AGT-Ⅱ values of all patients were measured by ELISA and radioimmunoassay. 30 cases with mild AP(MAP group),50 cases with SAP(SAP group) and 30 non-pancreatitis patients as control group. Results The level of TNF-α, IL-6, IL-8, PAF, AGT-Ⅱ of acute phase and recovery phase in SAP group and the MAP group were significantly higher than the normal control group(all P < 0.01); the level of TNF-α、IL-6、IL-8、PAF and AGT-Ⅱ of acute phase in SAP group were significantly higher than the MAP group(all P <0.05); the level of TNF-α、IL-6、IL-8、PAF and AGT-Ⅱ of re-covery phase in SAP group were significantly lower than the acute phase(all P <0.05);the level of TNF-α、IL-6、IL-8、PAF and AGT-Ⅱ of died in SAP group were significantly higher than the survivors (all P < 0.05～0.01). Conclu-sion The level of TNF-α、IL-6、IL-8 with the severity of SAP's condition and prognosis is closely related, The level of AGT-Ⅱ in SAP group were significantly higher than the MAP group.