Tuberculous sacroiliitis with no local abscesses or tuberculosis at other sites occurred in four patients, three men and one woman with a mean age of 42 years. Slow progression characterized this uncommon variant of joint tuberculosis. Two patients reported contact with family members known to have tuberculosis. Mean time from symptom onset to presentation was 14 months. Surgical biopsy showed epithelioid and giant-cell granulomas with caseous necrosis; culturing on Lowenstein-Jensen medium recovered the tubercle bacillus. Treatment was with antitubercular drugs, and protection from weight bearing for 4 weeks. These four cases illustrate the slowly progressive course of the clinical and radiological manifestations and underline the diagnostic difficulties met in the early stages of tuberculous sacroiliitis without tuberculosis at other sites. Antitubercular treatment can restore joint function provided the diagnosis is made before radiological destruction occurs.