Objective: To develop a sensitive method to detect minimal residual disease and to elucidate the significance of bcl-2 gene rearrangement in diagnosis and treatment of malignant lymphoma. Methods: Using polymerase chain reaction (PCR) to detect bcl-2 gene rearrangement and using serial dilution method to define the sensitivity of PCR. Results: In 9 different malignant lymphoma cell lines, Su-DHL-4 and Su-DHL-6 were shown bcl-2(MBR)/JH rearrangement, the sensitivity of PCR was 1:105. In 16 patients with follicular lymphoma, the peripheral blood and bone marrow were PCR positive in 4 cases both at initial diagnosis and after complete remission. Conclusion:Detection of bcl-2 gene rearrangement by PCR provides a sensitive and specific assay of minimal residual disease.It is helpful to improve staging of disease, prognosis and evaluation of the treatment results.