Samples used for this research were collected during the oceanographic cruises POP — EOCUMM ′95 (15 to 30 July 1995, N/O Italica) and carried out by a BIONESS multinet. Samples were taken on 8 stations, in lonian and in South Tyrrhenian Seas, across the Straits of Messina. All stations have been sampled at regular intervals of six hours (6.00 h; 12.00 h; 18.00 h; 24.00 h). The maximum sampled depth was 2030 m. A total of 5801 specimens of juvenile and adult euphausiids, belonging to 11 species (Thysanopoda aequalis, Meganyctiphanes norvegica, Euphausia krohni, E. brevis, E. hemigibba, Nematoscelis megalops, N. atlantica, Stylocheiron suhmi, S. longicorne, S. abbreviatum and S. maximum) were found and species composition of the two basins was related. N. megalops and E. krohni were the most common in the lonian Sea-Straits of Messina area, while in South Tyrrhenian Sea, T. aequalis, E. hemigibba and S. abbreviatum were the dominant species. Different abundance values and occurrence mean depths for juveniles and adults were underlined in the two areas just for the most important species. Day/night vertical distributions of the most representative species, in both areas, were studied.