The sea star, Dermasterias imbricata (Grube), was chemically attracted to its symbiotic scaleworm, Arctonoe vittata (Grube), in a Y-choice apparatus. The sea star consistently chose its symbiont over food, other Dermasterias sp., and Arctonoe fragilis. The specificity and regularity of the response suggest that the host, as well as the symbiont, may benefit from the association.