The aim of this work was to evaluate the usefulness of six potential reference genes in the Atlantic salmon. Salmonid fish are among the most widely studied model fish species in general, and extensive basic information on many different aspects of their biology has been collected [19] . Large-scale DNA-sequencing projects on salmon have been initiated in several laboratories http://www.sal mongenome.no/cgi-bin/sgp.cgi; http://web.uvic.ca/cbr/ grasp/; http://www.abdn.ac.uk/sfirc/salmon/; http:// www.bcgsc.ca/gc/salmon. In this work we selected the two 'classic' reference genes encoding GAPDH and β-actin, two genes encoding 18S rRNA and S20 ribosomal protein and two paralog genes encoding elongation factor 1A (EF1A A and EF1A B ). To evaluate their usefulness as reference genes, RNA from eight tissues of six adult salmon were subjected to real time PCR. The relative transcription levels of the genes were also estimated in four phases of young salmon going through smoltification, in order to check their stabilities under physiological stressful conditions.