Abstract Background: Diffuse large B-cell lymphoma (DLBCL) is the most common sub-type of Non-Hodgkin lymphomas (NHL) and it is a very heterogeneous group of diseases. CD5 positivity is profound in a substantial patient population in DLBCL. In this population, female patient distribution is higher, LDH elevation, extra nodal involvement, bone marrow involvement, ECOG (Eastern Cooperative Oncology Group) performance score elevation and high international prognostic score (IPI> 2) are more frequent for CD5 - DLBCL. Also, it was observed that prognosis of CD5 + DLBCL was worse than CD5 - DLBCL. We aimed to determine the frequency of CD5 positivity in DLBCL in Turkey with this multicenter study. Methods: The study, in order to get the overall parts from Turkey, including from each geographical area, 16 center and 9 cities were included. Each center retrospectively scanned the diagnostic pathology reports of DLBCL patients between January 2015-2021. Results: Two thousand four hundred sixty-nine DLBCL patients were screened retrospectively. CD5 positivity was detected in 169 patients (6.84%). The average age was 59 and 55.7% of the patients were male. Overall survival was 29.8 months. When evaluated with historical data in this group of patients, poor prognostic factors were found to be more common than CD5 - DLBCL patients. Conclusion: Due to its prognostic effect, immunohistochemically, the presence of CD5 in pathological samples of all DLBCL patients should be checked. The effect on prognosis in this patient group should not be forgotten while treatment and follow-up.