Recombinant DNA clones have been used to directly demonstrate that the Burkitt lymphoma cell line Raji, t(8;14) (q24;q32), has a rearranged copy of the c-myc gene adjacent to the gamma 1 constant region gene of the human immunoglobulin heavy-chain locus; the genes are arranged in the opposite direction for transcription. At least one further 5' exon has been detected in the normal c-myc gene by analysis of RNA transcripts, and the occurrence of high levels of two c-myc mRNA size classes, both apparently initiating in this exon, is described.