In this paper the first data on the composition, abundance and vertical distribution of developmental stages of euphausiids in the Adriatic Sea are presented. The research was performed in the deepest area of the southern Adriatic during all seasons. Hydrographic measurements confirmed that the annual temperature variations are limited to the surface layer up to 100 m in depth with minor salinity variations for the entire water column. Such stable hydrographic conditions contribute to maintaining a relatively constant composition of planktonic community in the southern Adriatic which makes these results on the seasonal distribution and abundance of euphausiid larvae representative for the open southern Adriatic. Out of the 12 formerly known euphausiids for the Adriatic and 13 known in the Mediterranean, developmental stages of 12 species were recorded. Minor deviations from the existing keys for euphausiid developmental stages were observed, and for this reason, we present their complement in the special chapter. Thysanoëssa gregaria has been reported in the Adriatic Sea for the first time. The most numerous species were: Thysanopoda aequalis, Euphausia krohnii, Stylocheiron longicorne, S. abbreviatum and Nematoscelis megalops. The maximum abundance of all developmental stages was determined in the spring. In comparison with the scarce data for the Mediterranean, we recorded higher abundance of euphausiids developmental stages in the Adriatic. Four migration patterns were observed: (i) nocturnal ascent to upper layers (calyptopes and furciliae: Euphausia brevis, E. hemigibba, E. krohnii, Nematoscelis megalops; calyptopes Nyctiphanes couchii; furciliae: Stylocheiron longicorne, S. maximum, Thysaönessa gregaria), (ii) migration to upper layers at midday and night, and descent during the morning and evening (calyptopes S. maximum), (iii) weakly-migrating or non-migrating population (calyptopes S. longicorne), (iv) irregular migration independent from the day/night cycle (calyptopes and furciliae: S. abbreviatum, Thysanopoda aequalis). According to the mean depth distribution, euphausiid developmental stages inhabit four depth layers (surface, sub-surface, mesopelagic and bathypelagic), and depending on the range of depth distribution they are characterized as scattered or non-scattered populations.