The diamondback terrapin (Malaclemys terrapin) is a coastal turtle with a range from Massachusetts to Texas and is the only exclusively brackish water turtle in North America. Two populations of wild terrapins from Maryland (n=55) and Georgia (n=7) were examined and tested for potential reptile pathogens. Whole blood and a mucosal (combined oropharyngeal and cloacal) swab from each animal were evaluated by quantitative PCR for 15 potential pathogens including frog virus 3, box turtle Mycoplasmopsis, Mycoplasma agassizii, Mycoplasma testudineum, Salmonella Enteritidis, Salmonella Typhimurium, Borrelia burgdorferi, Anaplasma phagocytophilum, tortoise intranuclear coccidia, testudinid alphaherpesvirus 2, terrapene herpesvirus 1, and terrapene adenovirus. Swabs were positive for a DNA segment 100% homologous to M. testudineum in both populations, with Maryland animals 87% (48 of 55) positive and Georgia animals 86% (6 of 7) positive. Although Mycoplasmopsis spp. are important respiratory pathogens for members of the order Testudines, none of the animals in the study showed any sign of upper respiratory disease. Our data suggest that M. testudineum may survive in non-Testudinidae turtles without causing clinical sigs of disease and suggesting appropriate precautions should be taken in facilities that house multiple species of turtles simultaneously.