The definition of primary splenic lymphoma is controversial, but it has been reported to be a rare disease that comprises less than 1% of all malignant lymphomas. Three cases of primary splenic diffuse large B-cell lymphoma treated at our institution are described here. Median follow-up was 34.6 months (range 8.7∼39.2) and median age at diagnosis was 72 years old (range 65∼73). In all three cases, the diagnosis was definitively established not by splenectomy but by ultrasonically guided percutaneous splenic tissue core biopsy. Using the Hans classifier, one of the cases was subclassified as the germinal center B-cell like (GCB) subtype and two as non-GCB subtype. One case was CD5-positive diffuse large B-cell lymphoma. Two patients were in Ann Arbor stage II and one was in stage III. Using the International Prognostic Index, one was categorized as Low/intermediate risk, one as high/intermediate risk, and one as high risk. All patients underwent eight cycles of rituximab plus cyclophosphamide, doxorubicin, vincristine and prednisolone followed by irradiation therapy. These three patients attained complete response. Although the follow-up period to date has been short, all patients have maintained a complete response and are currently alive. To determine whether our management protocol is valid, further observations are needed.