The sharks and chimaeroids are important members of the deep-water associations of fish of the continental slopes, but little is known about their trophic interactions. The diets of these fish were studied through the deployment of demersal trawls at successive 250 m depth intervals, within a total range of depth of 500 to 2 900 m, in the Rockall Trough to the west of Scotland and Ireland during the period 1975 to 1981. The sharks and chimaeroids, however, only occurred between 500 and 2000 m but principally in the 500 to 1 250 m bathymetric zones. These are the zones of maximum biomass of prey species of fish and probably also of prey species of epibenthos. The sharks divide into 3 trophic groups. Apristurus spp., Centroscymnus crepidater, Ttmopterus spinax and E. princeps exploit micronekton in the vicinity of the sea bed. Centroscyllium fabricii, Centroscymnus coelolepis, Deania calceus and Lepidorhinus squamosus are principally fish eaters. A third group may consist of 2 rarer species in the Rockall Trough, Galeus melastomus and G. murinus that exploit the epibenthos but also, to some extent, the micronekton. The 3 species of chimaeroids (Chimaera monstrosa, Hydrolagus mirabilis and Harriotta raleighana) prey on the epibenthos and the last species may also utilize, to some extent, infaunal species.