Introduction. Tuberculous (TB) synovitis is a rare, treatable, potentially lethal form of extrapulmonary TB resulting from massive lymphohematogenous dissemination of Mycobacterium tuberculosis (M. tuberculosis). We presented a case of TB synovitis of the knee in a Caucasian HIV negative man from Romania, a high TB incidence country. Case report. A 65-year old man presented with cough, high fever, mild wheezing, and swelling of the left knee. Chest radiography was normal. Sputum smears were Acid Fast Bacilli negative and Löwenstein-Jensen (L-J) culture negative for M. tuberculosis. Tuberculin skin test was negative. Respiratory symptoms disappeared in a week under antibiotics. Positive L-J cultures of knee punctation and favourable treatment outcome following standardized antituberculous treatment regimen confirmed the diagnosis of specific synovitis, which was also demonstrated by Magnetic Resonance Imaging (MRI). Conclusion. Tuberculous synovitis is important differencial diagnosis in patients with arthropathies and risk factors for TB in all the countries and all patients' ages even when tuberculin skin test is negative.