Splenic marginal zone lymphoma (SMZL) is a rare lymphoproliferative disease involving B-cells and affecting elderly patients. SMZL plague peripheral blood and bone marrow, spleen. Lymph nodes are generally spared. SMZL is due to a protracted antigen stimulation of B lymphocytes and of microenvironment leading B-cell to polyclonal and then oligoclonal/monoclonal growth, promoting lymphoproliferation. Integration of the NOTCH2 and NFk-B signaling has been recently identified as the primary mechanism of neoplastic proliferation in SMZL. In total 20% of cases carry mutations in NOTCH2. Although SMZL has an indolent course, progression to diffuse large B-cell lymphoma occurs in about 10-15% of patients. Establishing the prognosis is a key step in disease management, depending on both individual risk and patients' health status. This review discusses tailored treatment of SMZL patients. Progression risk factors include nodal and extra-nodal involvement, peripheral lymphocytosis, anemia and thrombocytopenia. Patients with two or more score points have a median survival of <5 years. Watch and wait strategy is appropriate in low-risk and asymptomatic patients, whereas treatment of symptomatic patients ranges from splenectomy to rituximab monotherapy or associated with chemotherapy.