We have determined the genomic structure of the human ribosomal protein L6 gene (RPL6) and assigned it to the interval containing the Noonan syndrome locus. RPL6 spans 4415bp and consists of seven exons and six introns. The first exon is only 19bp in length, containing a 5' non-coding region and a polypyrimidine tract. The second exon starts with the initiator ATG. Although the overall structure of the protein is highly conserved among mammalian species, there is significant variation in the N-terminal portion. We have refined the position of RPL6, using two different radiation hybrid panels. RPL6 was mapped to chromosome 12q24.1 between the markers D12S84 and D12S861, which is in the critical region for Noonan syndrome.