The prognostic significance of IgH/Bcl2 rearrangement in follicular lymphoma (FL) remains contentious; polymerase chain reaction (PCR) methodology and tissue source variability may account for some inconsistencies. As IgH/Bcl2 major breakpoint region (MBR) sequences may be found in normal blood, an MBR+ result by conventional PCR in blood/bone marrow may not indicate FL. To establish tumour MBR status, 190 lymphoid tissue samples with histologically evident FL (and therefore >1% tumour cells) were examined by real-time quantifiable PCR; 50% (95/190) had clonal MBR IgH/Bcl2 (MBR was considered clonal when >1%). Overall survival (median = 11.5 years) of MBR+ and MBR- patients was not significantly different.