Except in primary effusion lymphoma (PEL), serous effusions with lymphomatous cells in non-Hodgkin lymphoma (NHL) are not frequently seen as first manifestation of disease. In NHL lymphoplasmacytic lymphoma (LPL) the spleen, lymph nodes, and bone marrow are frequently sites of disease and this type of NHL is usually associated with a serum paraprotein of IgM type accompanied by the clinical syndrome of Waldenström macroglobulinemia. Our patient with NHL LPL type presented in this report had less frequently seen involvement of gastrointestinal tract and clinically was first manifested as effusion in Douglas space. Cytological evaluation as well immunoanalyses of effusion in such cases is essential, and various ancillary studies, because of differential diagnostic problems of lymphomas in serous effusions, first include reactive lymphocytoses and small round-cell tumors (SRCT). In our patient, cytology of effusion revealed cytomorphologically atypical lymphomatous cells with plasmocytoid differentiation. Immunocytochemical and flow cytometry analysis confirmed lymphoid cell differentiation and pathohistological diagnosis of CD20(+) LPL was set after pathohistological analysis of resected ileum.