The association between some infections and non-Hodgkin lymphomas (NHL) is well known. Human T-cell leukemia/lymphoma virus type 1 (HTLV-1) was the first oncogenic human retrovirus to be discovered and has been found to be associated with adult T-cell leukemia/lymphoma (ATLL). Epstein-Barr virus (EBV) has consistently been linked to both endemic and sporadic Burkitt lymphoma (BL), as well as to Hodgkin lymphoma (HL), post-transplantation proliferative disorders, extra-nodal NK-T-cell lymphoma (nasal type) and B-cell NHL arising in HIV patients; HCV infection is also associated to low-grade lymphoproliferative disorders that can progress to NHL. Bacterial infections have also been associated to NHL; chronic gastritis caused by Helicobacter pylori is responsible for mucosa-associated lymphoid tissue (MALT) NHL and high prevalence of Chlamydia psittaci infections has been reported in ocular adnexal lymphomas. In both these conditions, infection may contribute to the development of lymphomas, as proven by the clinical responses eradicating antibiotic therapies. Histological diagnosis coupled with immunohistochemical and molecular procedures are needed for a definitive diagnosis, but Fine Needle Cytology (FNC) combined with ancillary techniques can also produce correct diagnoses in most cases. In patients suffering from NHL, FNC also plays an important role in differential diagnosis between relapse of primary disease and reactive lymph nodes enlargement. This review explores the role of FNC in the diagnosis and classification of NHL trying to highlight possibilities and the limitations of the technique.