Splenic marginal zone B-cell lymphoma (MZL), with or without villous lymphocytes, is an indolent lymphoma, presenting with massive splenomegaly, generally associated with bone marrow dissemination. In patients requiring therapy, splenectomy has been reported as the treatment of choice. We reviewed the cases of 81 patients with splenic MZL. Patients presented with stage IV disease at diagnosis in 95% of the cases. Autoimmune events (hemolytic anemia, immune thrombocytopenia, acquired coagulation disorders, positive Coomb's test) were observed in 16 patients, and a monoclonal (M) serum component was detected in 46% of the patients. Twenty patients did not receive any initial treatment at diagnosis. Splenectomy was proposed in 79% of the treated patients, with adjuvant chemotherapy in 47% of patients. Median survival was 10.5 years and was significantly shorter in the presence of an M component, an elevated b2-microglobulin level, leukocyte count > 20000/microL, and lymphocytes > 9000/microL. Disease progression was significantly more frequent in patients presenting an immunological event or an M component. Seventy percent of the patients had persistent involvement of bone marrow and/or peripheral blood after splenectomy. Disease progression was significantly more frequent in partial responders than in complete responders (P < 0.005), but overall survival, risk of histologic transformation, and risk of death from lymphoma were not different in the 2 groups. Moreover, patients with cytopenia at diagnosis treated by splenectomy alone rapidly recovered normal hematological parameters. We conclude that splenectomy is an efficient treatment for splenic MZL, but that it may be delayed until the occurrence of symptoms or cytopenia.