Diseases of the respiratory tract commonly occur in captive chelonians, and several diseases also have occurred in wild chelonians. Infectious causes include viruses, bacteria, fungi, and parasites. Herpesviruses have surfaced as important pathogens of the oral cavity and respiratory tract in Hermann's tortoise (Testudo hermanii), spur-thighed tortoise (Testudo graeca), and other tortoises in Europe and the United States. Herpesvirus-associated respiratory diseases also have been reported in the green turtle, Chelonia mydas, in mariculture in the Cayman Islands. Of diseases caused by bacteria, an upper respiratory tract disease caused by Mycoplasma sp has been reported in free-hanging and captive gopher tortoises in the southeastern United States and in desert tortoises in the Mojave Desert of the southwestern United States. Mycotic pulmonary disease is commonly reported in captive chelonians, especially in those maintained at suboptimal temperatures. An intranuclear coccidia has been seen in several species of captive tortoises in the United States, and, in one case, a severe proliferative pneumonia was associated with organisms in the lung. The most common noninfectious cause of respiratory disease in chelonians results from trauma to the carapace. Although pulmonary fibromas commonly occur in green turtles with fibropapillomatosis, for the most part, tumors of the respiratory tract are uncommon in chelonians.