The amino acid sequence of the rat 60S ribosomal subunit protein L13 was deduced from the sequence of nucleotides in two recombinant cDNAs. Ribosomal protein L13 has 210 amino acids, the NH2-terminal methionine is removed after translation of the mRNA and has a molecular weight of 24,094. Hybridization of the cDNA to digests of nuclear DNA suggests that there are 8 to 10 copies of the L13 gene. The mRNA for the protein is about 870 nucleotides in length. Rat L13 is related to ribosomal proteins from other eukaryotes.