Tuberculosis of the thymus is extremely rare and is commonly mistaken for thymoma. We present a case of what we believe is tuberculosis of the thymus in a 62 year old woman, which was mistaken for a thymoma. The clinical, radiological and pathological findings are described, as well as review of the English literature. A diagnosis of tuberculosis is still possible, despite a negative confirmatory test. Preservation of tissue sample for culture may improve detection of tuberculous infection in resected anterior mediastinal masses.