Typical for the case history of a patient with the very rare vaccination-induced osteomyelitis is a relatively long interval between the BCG-vaccination and the initial clinical symptoms. The course of the disease is undramatic. Pronounced changes are frequently visible in x-rays and, with proper surgical and tuberculostatic therapy, the prognosis is good as well. The morphological changes in cases of BCG-osteomyelitis cannot be distinguished from those caused by tuberculosis. The same causal factors as for other possible BCG-complications are considered pathogenically significant for its development, perhaps as a result of a local trauma, too. When a BCG-osteomyelitis is suspected clinically, a curettage of the affected bone tissue is indicated for diagnostic as well as therapeutic purposes. A cause of BCG-osteomyelitis, diagnosed in a three-year-old girl, was described causally in detail.