CD153 (CD30 ligand) has been described as a 40-kDa type II transmembrane glycoprotein belonging to the TNF superfamily and is expressed primarily by activated T cells, B cells and monocytes. In this study, we have determined that the murine CD153 gene consists of four exons, with three intervening introns, spaced over approximately 26 kb of genomic sequence. Sequence analysis of the murine CD153 promoter and 5 flanking region revealed the presence of a TATA box element immediately upstream of two tsp sites, together with putative binding motifs for a variety of lymphoid-specific transcription factors. 5 RACE analysis of LPS-stimulated RAW264.7 macrophage cDNA identified at least four transcriptional start sites for murine CD153, with two sites occurring downstream of the previously predicted translation initiation codon. Additionally, 5 RACE analysis identified multiple murine CD153 polyadenylation sites. Our results indicate that primary murine CD153 transcripts may vary from 26 kb to approximately 28 kb in length.