The Green sea turtle leech, Ozobranchus brachiatus, infected a moribund hawksbill sea turtle (Eretomochelys imbricata) posthatchling juvenile at Farjardo, Puerto Rico. It usually infects green sea turtles, Chelonia mydas, and has not been reported from wild E. imbriata. A superinfection of the loggerhead sea turtle leech, Ozobranchus margoi, occurred on a stranded E. imbricata at Vieques Island, causing sea turtle leech erosion disease (SLED). We name and describe this disease for the first time. Ozobranchus margoi usually infects loggerhead sea turtles, Caretta caretta, and has not previously been reported either from the West Indies or confirmed from wild hawksbill sea turtles. In Barbados, O. margoi was first associated with a nesting female E. imbricata in 1997, and has been seen in other individuals since. SLED has not previously been reported from wild sea turtles or from the West Indies.