Objective To investigate the frequency of t(14;18) in different subtypes of B-cell lymphomas and the ability of the polymerase chain reaction(PCR) to detect this rearrangement in frozen samples. Methods 107 cases of B-cell lymphomas were studied using DNA extracted from fresh-frozen tissues. The DNA samples were amplified by PCR for bcl-2 MBR/JH. The products of bcl-2/JH rearrangement were hybridized with an internal olignucleotide probe of bel-2 MBR. Results The rearranged bel-2MBR/JH gene was detected in 13 of the 25(52. 0％) follicular cen ter lymphomas, according to REAL classification: 8 of 11(72. 7％) grade 1 , 2 of 5(40. 0％) grade Ⅱ , and 3 of 90 (33. 3％) grade Ⅲ. 17 of 82(20. 8％) cases of diffuse large B-cell lympbomas were found to have detectable bcl-2 MBR/JH rearrangement. Conclusion The frequency of bcl-2 MBR/JH rearrangement in diffuse large B-cell lym phomas is significantly lower than those in follicular center lymphomas(χ2=9. 28, P ＜0. 005), suggesting that bcl 2/JH rearrangements occur mainly in follicular center lymphomas. In addition, the result of reconstruction experi ments suggest that amplification of bcl-2 MBR/JH rearrangements by PCR is both sensitive and specific for detection of t (14 ; 18 ) translocation.