Abstract. – Within all plankton surveys, teleostean eggs are collected together with the plankton, but their identification is generally not considered because of the lack of knowledge in descriptive taxonomic key. Nevertheless, they can provide relevant information on biology and ecology of species, as well as on the condition of fishing stock in respect to fishery sciences. In the present work, we are proposing, for the first time, a determination key for fish eggs, based on qualitative, quantitative and ecological features to identify teleostean eggs of many species occurring in the Mediterranean Sea. Descriptors where followed and established while keeping alive eggs until hatching, since it get nearly always possible to determine the species or the genus to which they belong at the hatching stage and get back then to look for specific characteristics of the eggs.