We have isolated and characterized the single intron-containing gene encoding the mouse ribosomal protein S7. The mouse 129SV S7 gene has seven exons and six introns spanning about 5000 nucleotides. The exon-intron structure of the gene is similar to other vertebrate homologues. Southern blot analysis showed that in addition to the isolated single-copy intron-containing gene, there are 10-12 members in the mouse S7 gene family, which are all most probably processed pseudogenes. The promoter region of rpS7 contains several evolutionarily conserved putative regulatory elements. The main transcription start site was mapped to a T residue within a polypyrimidine tract, 79 nucleotides upstream from AUG codon.