DNA microarrays are currently in use almost exclusively as research tools for gene expression analysis and their application for the identification of organisms is still in its infancy, only documented by a few studies on mammals, bacteria, and viruses. The "Fish & Chips" project aims to demonstrate that DNA chips can be a new innovative tool for the identification of marine animals and phytoplankton. To achieve this goal, fishes, invertebrates, and phytoplankton were sampled in European seas and taxonomically classified. Fragments of their mitochondrial 16S, cyt b, and COI genes and from the nuclear 18S genes were sequenced and served as molecular markers to enable probe design for the microarrays. An on-line data base containing the sequences and all relevant information of the samples has been implemented. A first prototype of a “ Fish Chip „, Is based on more than 400 sequences from the 16S rRNA gene belonging to 46 species. A second microarray prototype serves to identify flatfishes from the North Sea based on COI-and 16S sequences from 70 individuals of 17 fish species. A “ Phytoplankton Chip Is now available with probes for all microalgal classes and many toxic species, as well as a “ Invertebrate Chip „. The results show that this approach is feasible.