Based on monthly samplings over an entire year, variations of abundance, vertical distributions and diel vertical migrations are described in the 0-1000 m water column in a coastal area of the Northwestern Mediterranean Sea for the main pelagic invertebrates. Detailed results are given for 21 species of macrozooplankton and micronekton. On an annual basis, the most numerous species by numbers comprised the euphausiid Meganyctiphanes norvegica, the pteropod Cavolinia inflexa, the siphonophores Abylopsis tetragona and Chelophyes appendiculata, the crustacean decapods Sergestes arcticus and Pasiphaea sivado, and the salps Salpa fusiformis and Thalia democratica. Species of the same genus, such as Sergestes arcticus, S. corniculum and S. robustus or Pasiphaea sivado and P. multidentata, occurred in maximum numbers at different times of the year. Eighteen out of the twenty-one species studied underwent a more or less extensive diel vertical migration. Some species, such as Meganyctiphanes norvegica and the pteropods Cavolinia inflexa, Clio pyramidata and Cymbulia peroni, showed monthly variations in their vertical distributions, migrating to deeper depths in certain seasons.