The infection of a variety of free-ranging wildlife species with Mycobacterium bovis, the causative agent of bovine tuberculosis (TB), can cause problems for biodiversity and species conservation. In some notable cases, particular species act as a reservoir of infection that can spill over into domestic livestock with economic and zoonotic consequences. Immunological methods for the detection of TB infection in wildlife are important for diagnostic and research purposes, especially where post-mortem examination is neither feasible nor desirable. In this review, the approaches taken to the immunological study of TB in wildlife species are summarized, with particular emphasis on their suitability for different applications and their applicability to different species. Different approaches to improving diagnostic sensitivity are discussed together with factors that can confound the use of tests in certain situations. Caution in the interpretation of test results for TB in wildlife is encouraged, especially where it has not been possible to confirm the accuracy of the test.