We present a 68-y-old female who had undergone aortocoronary bypass and developed Staphylococcus aureus sternal osteomyelitis. Despite prolonged therapy with different antibiotics and several local debridements and drainage, the wound remained open and suppurative. Only after sternectomy and wide excision of infected costal cartilage was the diagnosis of sternal tuberculosis made, 24 months later. This case illustrates the necessity of a high degree of suspicion to diagnose this very rare entity which coexists with more common causes of sternal osteomyelitis.