The c-yes-1 and bcl-2 genes have been independently mapped at the same position of the chromosome band, 18q21.3, which is a breakpoint in the t(14;18) chromosomal translocation. High-molecular-weight genomic DNAs and mRNA isolated from a follicular lymphoma cell line FL-18 and an Epstein-Barr virus harboring FL-18EB cell line, which carried the t(14;18), were analyzed. Although there was no detectable c-yes rearrangement, the chromosome 18-specific probe b (bcl-2) revealed one rearranged fragment after EcoRI, BamHI, PstI and SstI digestion. Therefore, breakage of chromosome 18 in the t(14;18) occurred at the SstI fragment containing the probe b sequence on the bcl-2 gene. The transcript of c-yes was undetectable, whereas active transcription of bcl-2 was observed in the FL-18 and FL-18EB cell lines at a higher level than in other types of lymphoma cell line. These data suggest that the c-yes-1 is not involved in the t(14;18), and the 2 genes located at 18q21.3 are independent sequences.