The tortoise tick Amblyomma marmoreum Koch was found to be established on a reptile facility in central Florida. Over a 5-mo period, 443 ticks were collected from tortoises, dogs, and vegetation. Collections from hosts were primarily from 3 species of exotic tortoises, including leopard tortoises, Aldabra tortoises, and yellow-footed tortoises. The total numbers of ticks present, the presence of all life stages, and the slow development of this species indicate that this is not a recent infestation. The source of the infestation is unknown because no tortoises were imported or moved onto this premise within the previous year. The propensity of this tick to feed on mammals and reptiles as immatures, its status as an experimental heartwater vector, and potential for further accidental introductions to the United States elicit concern toward the more widespread establishment of this species.