More than 100 species of gastropods from vent and seep localities around the world are reviewed, based on literature information and new material.The following new taxa are described (localities with parentheses, systematic position within brackets):Cantrainea macleanisp.n. (Louisiana Slope) [Turbinidae];Fucaria striatagen. et sp.n. (Juan de Fuca Ridge area),Vetuloniaphalcatasp.n. (North Fiji Basin) [both Trochidae];Protolira valvatoidesgen. et sp.n. (Mid‐Atlantic Ridge) [Skeneidae]; Ventsia tricarinata gen. et sp.n. (Lau Basin),Bruceiella globulusgen. et sp.n. (Lau Basin) [both tentatively in Skeneidae];Melanodrymia brightaesp.n. (Juan de Fuca Ridge area),Pachydermia sculptasp.n. (Lau Basin),Planorbidellagen.n.,P. depressasp.n. (Lau Basin),Ctenopelta poriferagen. et sp.n. (EPR 13°N)[Peltospiridae];Helicrenion reticulatumgen. et sp.n. (Lau Basin),Lepfogyra inflatasp.n. (Lau Basin) [families unknown];Desbruyeresia spinosagen. et sp.n. (Lau Basin),D. cancellatasp.n.(Lau Basin),D. melanioidessp.n. (Lau Basin),Provanna buccinoidessp.n. (Lau Basin) [Provannidae];Hyalogyra vitrinelloidessp.n. (Lau Basin),Hyalogyrina grassleis p a (Guaymas Basin)[Hyalogyrinidae fam. n.],Xylodiscula majorsp.n. (North Fiji Basin) [Xylodisculidae].The external morphology of the soft parts [for Ifremeria and Alviniconcha (Provannidae) also the anatomy] is described for most of the taxa involved.Some features in the biology and distribution of the gastropod fauna are discussed. About half the fauna consists of species belonging to families or superfamilies endemic to this environment. One‐fifth of the remaining species belong to taxa normally associated with biogenic substrates in the deep sea.Alviniconcha hesslerihas previously been shown to harbour chemosynthetic bacteria in the gill;Ifremeria nautileiis here confirmed to do the same.Ctenopelta porifera, andHirtopelta hirtaare suspected to have such bacteria because of reduction of the alimentary sy