Abstract: The high arctic Svalbard archipelago is characterized by a low insect species richness explained by both extreme living conditions and insularity. Here, we described two new species of Hymenopteran parasitoids found in Spitsbergen, the main island of Svalbard, using aphids as hosts. We named the first one Diaeretellus svalbardicum (Hymenoptera: Braconidae) because of morphological similarities with other European members of the Diaeretellus genus. D. svalbardicum parasitizes exclusively the aphid Acyrthosiphon svalbardicum, a species endemic to Svalbard. We also reported in D. svalbardicum a unique case of wing polymorphism with macropterous and micropterous forms in both genders. We named the second newly described parasitoid species Aphidius leclanti because of morphological similarities with other members of the Aphidius genus. Contrarily to D. svalbardicum, A. leclanti exploits the only two aphid species regularly found in Spitsbergen, A. svalbardicum and Sitobion calvulum.