The six major pests of oilseed rape, namely the cabbage stem flea beetle, the cabbage stem weevil, the rape stem weevil, the pollen beetle, the cabbage seed weevil and the brassica pod midge, are reported to host at least 80 species of hymenopteran parasitoids. Of these, 12 key species are widespread and abundant on oilseed rape crops throughout Europe; these species are important for conservation biocontrol of the pests on winter rape. This guide aims to help in their identification. It collates information from previously published keys, other literature and recent extensive examination of specimens and highlights selected key features of relevant taxa from superfamily to species. It is liberally illustrated with figures, newly-drafted and redrawn and/or modified from published literature. A glossary of terms is provided.