Tuberculous synovitis frequently presents as a monoarthritis of weight-bearing joints such as the hip, knee, or ankle. Owing to its low incidence in developed countries, the diagnosis is often delayed for months to years. Early diagnosis with a synovial biopsy permits prompt antituberculous therapy and substantially improves the prospect of preservation of joint structure and function. Initial treatment typically includes combination therapy with four drugs (isoniazid, rifampin, pyrazinamide, and streptomycin or ethambutol) because of the frequency of isoniazid resistance. Antimicrobial therapy should be of at least 9 months' duration, longer in immunocompromised hosts. Partial synovectomy and other surgical procedures should be restricted to joints with severe cartilage destruction, large abscesses, joint deformity, multiple drug resistance, or atypical mycobacteria.