Sjogren's syndrome (SS) is characterized by an increased risk of developing non-Hodgkin's lymphoma (NHL). Optimal treatment for NEL-complicating SS is not clearly established. NEL, which expresses the CD20 antigen on tumor cell surfaces, is a disease entity candidate to treatment with anti-CD20 monoclonal antibodies. We report clinical and immunological data of a patient with SS and NEL who was treated with a regimen consisting of cyclophosphamide/vincristine/prednisone (CVP) plus rituximab. A 68-year-old women had a 26-year history of SS and autoimmune thyroiditis. The clinical course of SS was complicated with severe splenomegaly. An increased percentage of CD19+ B cells (up to 30%) was detected in peripheral blood during follow-up. Clonal rearrangement of immunoglobulin heavy chain was detected. Low-grade B marginal zone lymphoma was diagnosed (peripheral blood immunophenotype: CD19 + CD20 + CD23 + sIg + Kappa; bone marrow immunophenotype: 25% lymphocytes; CD 19 + CD20 + CD79A/BCL2+). She received a total of six cycles of CVP plus rituximab (375 mg/m(2)). Therapy was well tolerated, and B lymphocytes were depleted from the peripheral blood. Splenomegaly normalized.