All newborns in Hong Kong are given bacille Calmette-Guerin vaccinations. Reported complications include formation of regional and extra-regional localised abscesses, osteomyelitis, and lymphadenitis. Several cases of bacille Calmette-Guerin osteomyelitis have been reported in Europe, but there are few reports of this in Asia. To the author's knowledge, this is the first case report of bacille Calmette-Guerin osteomyelitis in Hong Kong. Bacille Calmette-Guerin osteomyelitis, although rare, should be kept in mind as a potential complication of bacille Calmette-Guerin vaccination. Clinical suspicion, early diagnosis using an image-guided tissue biopsy and polymerase chain reaction study, and early commencement of chemotherapy are key to the effective management of this problem.