CD4+CD25+ T regulatory (Treg) cells constitute important elements of the tumor microenvironment of patients with Hodgkin (HL) and non-Hodgkin lymphoma (NHL), with characteristic expression of the transcription factor Foxp3. Elevated numbers of Treg cells in tumor tissues have been observed in various types of solid organ tumors and hematologic malignancies, including lymphomas. The aim of this study was to compare the proportion of Foxp3+ lymphocytes in fine needle aspirates of lymph nodes in patients with HL and NHL with a control group with benign reactive hyperplasia. In lymphoma (HL and NHL) patients we also analysed the correlation between the proportion of Foxp3+ lymphocytes and prognostic factors affecting the clinical course of the lymphoma (age, gender, clinical stage, size of the largest tumor, number of extranodal involvement sites, presence of B symptoms, hemoglobin concentration, and serum lactate dehydrogenase activity). The study involved a total of 137 participants, 34 with reactive lymphoid cell hyperplasia and 103 with lymphoma. The lymphoma patients group consisted of 31 patients with classical HL, 66 with B-NHL and six with T-NHL. The B-NHL patients were divided into two groups: patients with aggressive (n=36) and indolent B-NHL (n=30). The proportion of Foxp3+ lymphocytes based on immunocytochemical staining was expressed for all patients in two ways: as a percentage of the Foxp3+ cells (number of Foxp3+ cells / all lymphatic cells) and as a ratio between the percentage of Foxp3+ cells and CD3+ cells (number of Foxp3+ cells / T cells). The highest percentage of Foxp3+ cells was found in the group of patients with classical HL, with a statistically significant difference in comparison to patients with aggressive and indolent B-NHL. Contrary to expected results, the percentage of Foxp3+ cells found in the group of B-NHL patients was lower than in the group of patients with reactive hyperplasia. However, when the proportion of Foxp3+ lymphocytes was expressed as a ratio between the Foxp3+ cell percentage and CD3+ cell percentage, a statistically significant higher value was found in patients with indolent B-HNL and a borderline significant higher value in patients with aggressive B-HNL in comparison to reactive lymphocytic hyperplasia. In the lymphoma patient group, higher percentage of Foxp3+ cells correlated with favorable prognostic factors, such as early clinical stage, size of the largest tumor <10 cm, and no involvement of extranodal sites. In the group of patients with NHL, increased percentage of Foxp3+ cells also correlated with favorable prognostic factors, such as early clinical stage and size of the largest tumor <10 cm. However, in patients with classical HL there was no statistically significant association between the proportion of Foxp3+ lymphocytes and any of the prognostic factors investigated.