An 88-year-old Japanese woman with splenomegaly, but without lymphadenopathy, was admitted because of epigastric distress. Laboratory data disclosed an RBC of 310 x 10(4)/microliter, Hb of 10.1 g/dl, Ht of 30.6%, Plt count of 9.8 x 10(4)/microliter, and WBC of 4,470/microliter with 38% abnormal lymphocytes. Peripheral blood films revealed lymphocytes with thin, short cytoplasmic villi, condensed nuclear chromatin, and small nucleoli. The lymphocytes stained negative for tartrate-resistant acid phosphatase. Also, immunophenotyping was positive for expression of the cell surface markers CD19, CD20, IgG, kappa and HLA-DR, but not for CD5, CD10, CD11c, CD23, CD25, CD38, or CD103 antigens. Chromosomal analysis of peripheral blood cells disclosed the 46, XX, del(7), (q32) aberration. A splenectomy was performed simultaneously with partial colon resection because of a mucinous carcinoma found in the transverse colon. Histologic examination of resected spleen tissues revealed a distinctive pattern of white pulp infiltration by lymphoma cells. The histologic findings and clinical data were consistent with the features of splenic lymphoma with circulating villous lymphocytes. Our patient exhibited a relatively benign clinical course, and was being followed on an outpatient basis with no additional therapy.