A 72-year-old man presented with a 6-month history of low back and leg pain. Past medical history revealed transurethral resection of bladder cancer followed by multiple intravesical BCG instillation 12 years ago. Imaging studies of the thoracolumbar spine showed osteolysis of the L3 and L4 vertebrae and the associated intervertebral disc space, and a large soft tissue mass with signal abnormalities suggesting of an abscess. CT-guided needle biopsy showed Mycobacterium bovis infection. A triple anti-tuberculous chemotherapy regimen including isoniazid, rifampicin, and ethambutol was administered for 12 months. Surgical treatment included drainage of the abscess and L2-L5 spinal instrumentation and fusion. Intravesical BCG therapy may be complicated by late disseminated disease to the bone even many years after initial BCG therapy. Patients having BCG therapy should be closely evaluated thereafter for the possibility of hematogenous spread of mycobacteria to distant sites.