Mislabeling of North American merlucciid hakes in stock surveys and commercial market samples was detected by employing nuclear 5S ribosomal DNA (rDNA) and mitochondrial cytochrome b variation as molecular markers. Results showed that offshore hake Merluccius albidus is sold in European markets but is labeled as the morphologically similar silver hake M. bilinearis, which is the target species of the fishery. This suggests that offshore hake may be inadvertently included within silver hake landings, as the two species overlap in the southern area of silver hake distribution (approximately 41°-35°N latitude near North American coasts). An inexpensive and technically easy technique based on polymerase chain reaction (PCR) amplification of a fragment of S rDNA and visualization of PCR products in agarose gels is recommended for routine species assignation in landings for purposes of exploitation estimates and for authentication of commercial hake species.