The genomic organization for the human P2X7 receptor gene was determined to comprise 13 exons. Alignment of the exon-intron junctions with those for the rat P2X2 gene demonstrated a precise conservation of the boundaries for the first 10 introns. The human P2X7 receptor gene was localized by in situ hybridization to chromosome 12q24. Radiation hybrid mapping indicated that this is within 130 kb of the gene for the homologous P2X4 receptor.