We have determined the genomic sequence of the entire mouse TNF locus, which comprises the genes for TNF-a, the macrophage-derived tumor necrosis factor, and TNF-P, also known as lymphotoxin. The derivation of the genomic clones used for the sequence determination has been described previously (1). The sequence presented here differs from a previously published mouse TNF-P sequence (2) by the insertion of a 48 bp BamH I fragment at positions 1274 to 1322. It also presents the intergenic sequence between the TNF-P and the TNF-a genes. The following features are indicated (above the sequence): a Bl repetitive element located 5'to the TNF-b gene; the" TATA"(Goldberg-Hogness) boxes upstream of the RNA initiation sites; the putative RNA initiation sites; the positions of intron/exon junctions; the" TTATTTAT" elements in the 3'untranslated regions that have been repoted to reduce the stability of the mRNAs (3); the polyadenylation signal sequences. The amino acid translation of the coding regions is indicated below the sequence.