SOX11 is a transcription factor involved in embryonic neurogenesis and tissue remodeling. Its role in lymphopoiesis is still unknown. Recent studies have shown the specific overexpression of SOX11 mRNA and nuclear protein in both cyclin D1-positive and -negative mantle cell lymphoma (MCL). In addition to MCL, SOX11 is strongly expressed in hairy cell leukemia, Burkitt lymphoma, and immature lymphocytic neoplasms. Expression of SOX11 in MCL is not only a new diagnostic marker, but may also carry information related to the clinical and biological behavior. Further study of the biology may reveal common pathways to neoplasia related to SOX11 expression.