Previous studies have suggested that CD30 may be expressed in diffuse large B-cell lymphomas (DLBCLs). However, the prevalence of CD30 + DLBCLs and extent of CD30 expression within an individual tumor have not been fully evaluated. The aim of this study was to determine the frequency and extent of CD30 expression in DLBCLs, and explore possible relationships between CD30 expression and clinical and biologic variables. We retrospectively identified and analyzed 167 cases of CD30 + DLBCLs from our pathology archive. Twenty-one percent (95% confidence interval [CI]: 14.8-27.1%) of these cases expressed CD30, and in 52% of them CD30 was positive in > 80% of tumor cells. CD30 expression was more frequent in DLBCLs with non-germinal center origin phenotype, BCL2 + DLBCLs and in patients ≤ 47 years old. There was significant interaction of BCL2 expression with age and subtype of DLBCL. A multivariate analysis performed in BCL2 + DLBCLs showed a higher frequency of CD30 + cases in non-germinal center DLBCLs (odds ratio [OR]: 6.5, 95% CI: 1.1-36.5) and in patients ≤ 47 years old (OR: 6.9, 95% CI: 1.5-29.5). These associations could suggest a common biologic pathogenesis. The effectiveness of anti-CD30 drugs in other lymphomas opens the possibility for their use in patients with CD30 + DLBCLs.