Stage I/IIA follicular lymphoma (FL) is considered a localized disease that can be adequately treated with radiotherapy alone. This strategy is recommended by the guidelines of the "Società Italiana di Ematologia" (SIE) and of the "European Society for Medical Oncology" (ESMO) The accurate definition of the truly localised forms represents a crucial issue in order to ensure an appropriate treatment design for such patients. The characteristic t(14;18) translocation, which leads to the over-expression of the Bcl-2 gene, is found in approximately 85% of FL; cells bearing this translocation can be detected in the peripheral blood (PB) or bone marrow (BM) by polymerase chain reaction (PCR).