First finding of brittle star Ophiocnemis marmorata in jellyfishes of genus Rhopilema in waters of Vietnam is described.      Symbiosis between scyphomedusae and epizoic invertebrates, in particular with hyperiid amphipods, has long been known (Thiel 1976). However, the association of echinoderms with jellyfish is unusual and has seldom been reported.      Russian investigators worked in the Nhatrang Bay near the Tam Island in 2011. Underwater they could meet enough greater number Scyphozoa jellyfishes Rhopilema hispidum (Vanhöffen, 1888).      Inside of a bell of many jellyfishes were visible brittle stars. One such jellyfish was placed in a bucket under water and delivered aboard a vessel together with all symbionts. Among symbionts there were 9 juvenile fishes, 7 swimming crabs Charybdis feriata (Linnaeus, 1758), 4 shrimps and 5 brittle star specimens Ophiocnemis marmorata (Lamarck, 1816).