['To analyze CD5 expression in diffuse large B cell lymphoma (DLBCL) and to explore its relationship with the clinicopathological characteristics.', 'The clinical data from 160 DLBCL patients who were treated in First Bethune Hospital of Jilin University from January 2001 to December 2010 were retrospectively analyzed. Immunohistochemical staining (SP method) for CD5, CD10, bcl-6 and MUM-1 was performed on the paraffin-embedded tissue. The relationship between CD5 expression and the clinicopathological characteristics was evaluated by Chi-square test. Survival analysis adopted Kaplan-Meier analysis and Log-rank test.', 'In the patients aged 60 years or older, the incidence of CD5(+) lymphoma (12/17) was significantly higher than that of CD5(-) ones (39.9%, 57/143); two or more extranodal involvements in CD5(+) patients (11/17) were more commonly found than that of CD5(-)patients (31.5%, 45/143); DLBCL-related death in CD5(+) patients (13/17) was higher than that of CD5(-) patients (37.1%, 53/143). Survival analysis showed that the overall survival (OS) and the event-free survival (EFS) of CD5(+) patients were significantly lower than those of CD5(-) patients. In the condition of different GCB type, different therapy and low IPI (0 ∼ 2), the OS of CD5(+) DLBCL patients was significantly lower than that of CD5(-) patients, while in the condition of high IPI (3 ∼ 5), the OS of CD5(+) and CD5(-) DLBCL patient had no obvious difference.'] Is [ CD5 expression an adverse prognostic factor in diffuse large B-cell lymphoma ]?