Objective To detect the A20 gene deletion,investigate the impacts of A20 gene deletion on clinicopathological features and prognosis of DLBCL,and relationship between activation of NF-κB pathway and relative molecular pathogenesis.Methods A20 gene deletion was detected by fluorescence in situ hybridization (FISH).The expression of A20,Survivin,P65 and Ki-67 were detected by immunohistochemistry stain.Apoptosis was assayed by TUNEL.Follow-up and statistical analysis were done.Results The deletion rate of A20 gene was 21.7％.The deletion rate of A20 gene was obviously higher in ABC-like DLBCL than that in GCB-like DLBCL (30.6％ vs.8.3％,P＜0.05).It was observed that there was a negative correlation between A20 protein expression and A20 gene deletion (r=-0.259,P =0.023).The expression of P65 and Survivin protein was positively correlated with the A20 gene deletion (r=0.280,P =0.015;r =0.313,P =0.007).Apoptosis rate was significantly reduced in DLBCL patients with A20 gene deletion.The apoptosis rate was higher in cases with positive expression of A20 protein,while that was lower in cases with positive expression of p65 and Survivin protein than those with negative expression of corresponding protein.There was no statistically significant difference in apoptosis rate between ABC-like and GCB-like DLBCL patients (P＞0.05).COX regression analysis indicated that age,A20 gene deletion,types of DLBCL and Ki67 expression were independent factors associated with survival status.Log-rank test showed that there was a statistical difference in survival status between the cases with and without A20 gene deletion (P=0.015).Conclusion A20 gene deletion may associate with the attenuation of A20 protein expression.The latter weakens negative feedback regulation of A20 protein for NF-κB pathway.An up-regulated expression of Survivin and abnormal proliferation and apoptosis may be result from the abnormal activation of NF-κB.A20 gene deletion brings certain influence on clinical course and prognosis of DLBCL.