Background: Regulatory T cells (Tregs) are a specialized subpopulation of CD41 T cells which maintain the immune system homeostasis. They may increase during cancer progression and have been correlated with a worse prognosis in many malignancies. However, the role of Treg cells in lymphoma is debated.Methods: In this study, we assessed the peripheral blood levels of CD41 CD251 FOXP31 Tregs in newly diagnosed patients with lymphoma and tried to find a relationship with patient characteristics. Twenty one patients with Hodgkin lymphoma (HL), 40 patients with non Hodgkin lymphoma (NHL) and 30 healthy sex matched controls were included in the study. Analysis were done by 3-color flow cytometry and only helper T cells were selected directly using CD4perCP as a gating strategy.Results: In HL group; there was a positive correlation with IPS, CRP, LDH and negative correlation with albumin, absolute lymphocyte count. Tregs were higher in male HL patients. In NHL group; there was a positive correlation with stage, IPI, CRP, LDH and a negative correlation with albumin ve absolute lymphocyte count.Conclusions: There is a relationship between peripheral blood Treg levels and some poor prognostic parameters in newly diagnosed lymphoma patients. This relationship suggests a possible prognostic role of Tregs in lymphoma. Further research is needed in determining how to use Tregs as a prognostic factor. V C 2015 International Clinical Cytometry Society