Objectives: The aim of this study was to determine the number of newly diagnosed Non-Hodgkin's B lymphomas in a five-year period at the Clinical Institute for Pathology and Forensic Medicine at the Clinical Hospital Center Osijek. To determine the frequency of B-cellular Non-Hodgkin's lymphomas in relation to gender, age and type. Study design: Cross sectional study with the archive data. Participants and methods: The research included 183 examinees with the newly discovered Non-Hodgkin's B lymphoma. Existing medical documentation (archive) was analyzed together with archival histological samples stained using both standard (haematoxylin-eozin) and immunohistochemical (IHC) methods. For immunohistochemical tissue processing a Ventana Benchmark Ultra automated stainer from the company Roche and monoclonal primary antibodies from the company Roche were used. In all samples the type and localization of NH B lymphomas were determined with the help of an Olympus® microscope, model CX40. Results: In the period from January 1st, 2014 to December 31st, 2018, 183 B-cellular NHLs were diagnosed. The majority of examinees belonged to the 60 - 69 age group (68/37 %), with the median age of 64 years. The most common type of NH B lymphoma was DLBCL (50 %). The largest number of NH B lymphomas was diagnosed in the lymph nodes (57 %), of which 43 % were neck nodes. Extranodally NH B lymphoma is most commonly diagnosed in the GIT (49 % of cases). The most commonly used marker was CD20 with positivity in 178 subjects (97 %). All subjects, 144 of them (100 %), who underwent a CD3 marker showed a negative result. Conclusion: This retrospective study indicates the need to create a registry of patients with B-cell Non-Hodgkin's lymphoma according to the current WHO classification.