Abstract: Objective To study the morphological and cytogenetic characteristics of the follicular lymphoma(FL) grade 3B and the association of disease pedigree between the follicular lymphoma grade 1-3A and the diffuse large B-cell lymphoma(DLBCL) . Methods Thirty-fi ve FL and 9 GCB-DLBCL were detected by fluorescence in situ hybridization(FISH) and immunohistochemistry . The BCL2/IGH fusion and the BCL6 separation were researched respectively by FISH. BCL2 and BCL6 proteins were detected by immunohistochemistry. All their statistical comparisons were conducted by SPSS13.0 Software. Results The prevalence of BCL2 fusion was lower in FL3B compared with FL1-3A(27% vs. 86%, P＜0.05) . BCL2 protein expression rate was less in FL3B than that in FL1-3A (45% vs. 96%, P＜0.05). There was no correlation between BCL2 protein expression and BCL2/IGH fusion, as well as BCL6 separation in each group. Conclusion The follicular lymphoma grade 3B had an intermediate morphological form between the follicular lymphoma 3A and the diffuse large B-cell lymphomas .The cytogenetic change of FL3B was closed to diffuse large B-cell lymphomas. The lower BCL2/IGH fusion rate of FL3B suggested that FL3B had a different carcinogenic. pathway from FL1-3A and the diffuse large B-cell lymphomas.