The expression of trans-acting small RNAs in firmicutes has been poorly documented to date. This gap is being filled quickly in the genus Staphylococcus, which is both a model firmicute and an important human pathogen. Here we analyze RsaOG, a novel small RNA family specific to Staphylococcus and highly transcribed. This well conserved element, first discovered in a computational screen, was precisely mapped in the genome by RACE mapping and the identification of a putative transcriptional promoter. The proposed secondary structure presents two highly conserved unpaired sequences, part of which can form a pseudoknot. We suggest a possible involvement of the remaining conserved single stranded region in trans regulatory interactions.