A gene for the Paracentrotus lividus ribosomal protein S24, called P1-S24, has been isolated and sequenced. Ribosomal protein P1-S24 consists 130 amino acids and has a molecular weight of 14869 Da. Sequence analysis shows a high percentage (90%) identity with the corresponding gene of Strongylocentrotus purpuratus. Hybridization of the cDNA to digested sperm DNA suggests that P1-S24 is represented in no more than two copies. Studies of the temporal expression of P1-S24 gene indicate a good correlation between this and the expression of the rRNA genes both during oogenesis and embryonic development.