We previously reported the sequence of YL8A, one of the two genes encoding yeast ribosomal protein YL8. With the aim of conducting an evolutionary study we have cloned and sequenced a second gene, YL8B. The disruption of both genes is lethal. Unlike other duplicated ribosomal protein genes, each open reading frame is interrupted by two introns containing long conserved sequences. A comparison of nucleotide and amino-acid sequences reveals that the duplication of the YL8 gene must have occurred very recently. Alignment and phylogenetic analysis of the amino-acid sequences of YL8-related proteins from various species show the existence not only of YL8 ribosomal proteins but also of a family of YL8-like proteins. These are present in at least three species of yeast and seem to be functionally distinct from ribosomal proteins.