The earliest known case of human tuberculosis in Britain dates to the middle period of the Iron Age, approximately 2,200 years before present. Bone lesions on the spine of a male skeleton excavated at Tarrant Hinton in Dorset, United Kingdom, show evidence of Pott's disease and are supported by molecular evidence of Mycobacterium tuberculosis complex DNA amplified by IS6110 PCR (19). In the present study, we used a further series of sensitive PCR methods to confirm the diagnosis of tuberculosis and to determine the genotype of the infecting strain. These tests demonstrated that this individual was infected with a strain of M. tuberculosis rather than Mycobacterium bovis. The strain had undergone the tuberculosis D1 deletion affecting the mmpS6 and mmpL6 genes and can therefore be identified as a member of the family of "modern" M. tuberculosis isolates. All evidence obtained was consistent with surviving mycobacterial DNA being highly fragmented in this case.