The early larval stages of the deep-sea Nematocarcinidae, Nematocarcinus longirostris Bate, 1888, from the south-western Atlantic Ocean, and N. lanceopes Bate, 1888, from the high Antarctic Weddell Sea, were obtained from plankton catches, described and illustrated. Furthermore, field collected larvae of N. lanceopes were compared with larvae hatched and reared under constant laboratory conditions. Morphology of larvae in both species clearly indicates a planktotrophic and extended mode of larval development. This is an outstanding feature in deep-sea and especially in high-latitudinal caridean shrimp species, and the consequence of such reproductive trait for life history adaptations to both deep-sea and polar environments is discussed.