A better knowledge on spawning grounds of principal commercial fishes from North Sea is necessary for their monitoring. Fish egg taxonomic identification based on morphological characters cannot always be carried out effectively. This is particularly the case for a number of Gadidae fish species eggs (i.e. cod, haddock and whiting, and three rockling species) which have the same range of size and for which molecular-based techniques can help improving the accuracy of egg taxonomic identification, and hence the reliability of studies on spawning areas. In this study, formalin fixation, egg conservation and DNA extraction were optimized in order to develop a specific PCR-RFLP method. Based on the sequence of the cytochrome b gene of reference specimens, a PCR-RFLP method was developed to distinguish eggs of cod, haddock and whiting of one part, and between eggs from three species of rocklings on the other part. Among the 404 eggs tested, 80% of positive amplification was obtained for rocklings eggs and 86.36 % for Gadidae eggs. Eggs from Enchelyopus cimbrius, Ciliata mustela and Ciliata septentrionalis, and Gadus morhua, Merlangius merlangus and Melanogrammus aeglefinus were distinguished. with this method. Based on morphological characters, the percentage of misidentification was less for cod than whiting.