Agriotypinae is a small clade of aquatic parasitoid wasps with uncertain affinities. Its phylogeny was examined in a cladistic analysis of larval and adult morphological characters. The analysis found that Agriotypinae belongs within Ichneumonidae as sister group of Labeninae and related to Xoridinae and Cryptinae. All sixteen species in the subfamily should be assigned to Agriotypus Curtis. Two species groups were found, the Palaearctic armatus species group and the Oriental himalensis species group. Agriotypus chaoi** sp.n. and Agriotypus masneri** sp.n. are described from Vietnam and Atopotypus** Chao is synonymized with Agriotypus forming Agriotypus succinctus** (Chao) comb.n. A key and revision of the world species is provided, and the evolution of aquatic behaviour in Ichneumonidae is discussed.