Luidia ciliaris (Philippi) has intraoral digestion and was found to be a selective feeder on echinoderms. In 258 specimens from the Irish Sea, echinoderms occurred in 97·4% of all stomachs containing food and contributed 92% of the food volume (estimated by points method). The most important food items were Psammechinus miliaris, Ophiothrix fragilis, Ophiura albida and Ophiocomina nigra. Ophiocomina nigra did not occur as frequently as would be expected from their availability. Observation in situ revealed that large specimens had efficient escape response to moving Luidia and aquarium experiments showed that O. nigra deprived of their moving ability were readily eaten. However, the Luidia showed clear preference to Ophiothrix fragilis. There was no distinct seasonal difference in the composition of the diet, but a tendency to a minimum feeding activity in May-June, probably connected with the spawning period.