Background: Bacillus Calmette-Guérin (BCG) is a live attenuated strain of Mycobacterium bovis and has been used for intravesical treatment of superficial bladder cancer since 1976. Systemic complications of intravesical BCG are rare, and vertebral osteomyelitis has only been described in 10 prior cases worldwide.Case: A 64-year-old white man with benign prostatic hyperplasia was diagnosed with transitional cell bladder cancer and underwent transurethral resection of bladder tumor. He received perioperative mitomycin C followed by a 6-week course of intravesical BCG. Recurrent bladder cancer was noted on follow-up cystoscopy and he was started on a second 6-week course of BCG. Before the second intravesical BCG, he developed night sweats and severe progressive back pain with bilateral lower extremity weakness. Magnetic resonance imaging of the spine revealed a T11 to T12 vertebral body destruction with discitis, and biopsy revealed M bovis BCG. He received therapy with isoniazid, rifampin, capreomycin, as well as ethambutol and, later, additional drugs (cycloserine, moxifloxacin) secondary to clinical and radiographic progression of disease. He underwent a T11 to T12 vertebrectomy and continued on isoniazid, rifampin, cycloserine, and moxifloxacin for a total of 12 months postoperatively.Conclusions: Mycobacterium bovis BCG osteomyelitis is a rare complication of intravesical BCG therapy for bladder cancer and may occur as a solitary site of infection. A high degree of suspicion is important in patients with osteomyelitis with a history of transitional cell cancer managed with immunotherapy using BCG instillations.