Background: Vitamin D is a steroid that has long been implicated in calcium homeostasis and bone mineralization.Aside from its classical roles in healthy individuals, Vitamin D has been shown to exhibit numerous anticancer and immunemodulating properties. The aim of this study is to evaluate the level of vitamin D in Egyptian lymphoma patients , as well as to evaluate the value of vitamin D replacement in vitamin D-insufficient lymphoma patients regarding response to chemotherapy.. Patients and methods:The study was conducted on 100 patients with Diffuse large B cell lymphoma (DLBCL) collected from Internal Medicine Department, Oncology and Hematology Unit at Benha University Hospital during period from February 2020 to May 2022, ptients with established diffuse large B cell lymphoma diagnosed according to WHO guidelines. Results: There was Significant relation between the studied groups and disease stage (P = 0.018), KI-67 (P = 0.031), and IPI score (P < 0.001). After treatment, vitamin D revealed an overall significant difference between groups. A significant association was reported between the studied groups and complete response (P = 0.03. Those with non responsive disease revealed significantly higher age (52 ±6 years vs. 44 ±11 years, P = 0.047) and male predominance (100% vs 60.2%, P = 0.044). In addition, a significant association was reported between non responsive and IPI score (P = 0.002. Conclusion: vitamin D may have a prognostic index & showed asssosiation between it,s deiciency & lymphoma agressivenes also vitamin D replacement might have a role to iprove outcome of treatment.