AbstractWe describe a t(8;14)(q24;q11) involving the T‐cell receptor α‐chain gene (TCRA) and the 3′ region of theMYCprotooncogene in a B‐cell lymphoma. The B‐cell origin of this tumor was determined by its histological architecture, by immunophenotypic analysis, and by Southern analysis of immunoglobulin gene rearrangements. An identical fragment encompassing the translocation breakpoint junction was detected through Southern analysis using both aTCRAJ and aMYCprobe. The other alleles at theTCRAJ andMYCloci were in the germline configuration. Restriction enzyme and nucleotide sequencing analyses revealed that the breakpoint junction on chromosome 8 lies approximately 700 base pairs (bp) downstream of the 3′ end of the thirdMYCexon; on chromosome 14, the break is located 12.6 kilobases (kb) downstream of the 3′ end of the Cδ fourth exon. A heptamer‐like consensus sequence on chromosome 14 adjacent to the translocation breakpoint implies the involvement of recombinase activity. However, no consensus sequences were found on chromosome 8 within 140 bp in either direction from the breakpoint. It is possible that this translocation involvingMYCoccurred during an attempt at an inappropriate rearrangement of theTCRAlocus in a cell