BCG osteomyelitis is rare comlication and the incidence rate has been estimated to be 1/milion vaccinated neonate and infants. BCG osteomyelitis is also reported as a complication of intravesical BCG treatment for bladder carcinoma. We had experienced a 14 months old infant who presented swelling, tenderness and redness on left upper arm suspicious due to BCG vaccination. The MRI finding showed $2{ imes}4{ imes}4cm$ subcutaneous abscess with cortical defect on proximal humerus and axillary lymph adenopathy. The histologic finding showed diffuse caseous necrosis and Langhans type giant cell. We report A case of BCG osteomyelitis.