Abstract: Objective To investigate the different expressions of Ki-67 between diffuse large B cell lymphoma (DLBCL)and the reactive hyperplasia of lymphnode (RH),germinal center B cells (GCB)and non-GCB types,and to explore the clinical significance of Ki-67.Methods Samples from 60 DLBCL patients served as observation group,while the other 20 tissue samples from patients with lymphoid reactive hyperplasia as control group.The difference of Ki-67 expres-sions between GCB and non-GCB were compared and the relationships between Ki-67 expression and DLBCL,the international prognostic index (IPI),short-term efficacy and prognosis were analyzed. Results The average expression rate of Ki-67 was (69.17±14.73)%and (40.50±14.95)% in observation and control groups respectively ,and the difference was significant (t= 7 .5 0 9 ,P<0.0001),and it was (59.29±14.92)%and (71.96±13.39)%in GCB and non-GCB groups (t= 3.019,P= 0.0038)and (65.29±15.17)% and (74.23±12.70)% in IPI<2 and IPI≥2 groups (t= 2.422,P= 0.0186),respectively.Conclusion The abnormal expression of Ki-67 is closely associated with clinical stages,index of IPI,types,short-term effect and prognosis in DLB-CL,which plays an important role in the diagnosis,treatment and prognosis of DLBCL.