The etiology of sarcoidosis has not yet been established, but several mycobacterial species have been implicated in the pathogenesis of this disease. We have used a nested primer polymerase chain reaction (PCR) specific for the IS900 Mycobacterium paratuberculosis insertion element to analyse paraffin-embedded mediastinal lymphoid tissue from 18 patients with pulmonary sarcoidosis verified by mediastinoscopy. Only the positive control contained M. paratuberculosis-specific DNA. The present study does not support a role for M. paratuberculosis in the pathogenesis of sarcoidosis. However, further studies are needed in order to clarify the possible role of other mycobacteria in this disease.