A 12-year-old PPD-negative girl developed bilateral optic neuritis with decreasing visual acuity 5 days after bacille Calmette-Guérin (BCG) vaccination. Laboratory findings and computerized tomography scan of brain and orbit were negative. Cerebrospinal fluid study revealed 62 leukocytes (92% lymphocytes) per cubic millimeter and a protein level of 33 mg/dl. The patient was treated with systemic steroids. The vision returned to normal in 4 weeks and the disc edema resolved in 6 weeks without residual deficit. The complications of BCG are discussed.