BCG-osteomyelitis is a rare complication of BCG-vaccination. By means of a case report clinical and immunological findings are discussed. Contrary to the undramatic clinical symptoms the x-ray showed pronounced osteolytic lesions in the sternum. The bacteriological examination demonstrated mycobacteria of BCG-type. Immunological investigations presented normal humoral and cellular immunity. The therapy (curettage, antituberculous drugs) was effective. In spite of this complication the BCG-vaccination is furthermore recommended.