Pyomyositis is a primary bacterial infection of the skeletal muscles. Although infection can affect any skeletal muscle, the large muscle groups such as the quadriceps or gluteal muscles are most often the focus of this disease, and most commonly the inflammation is focal, involving a single muscle. The mechanism of pyomyositis is poorly understood. The local mechanical trauma at the time of an incidental bacteremia is frequently postulated as a mechanism that could explain the high incidence of the disease in tropical areas and its male preponderance. Staphylococcus aureus is the most common organism responsible for pyomyositis. Mycobacterium tuberculosis primarily affects the lungs, and the prevalence of active pulmonary tuberculosis co-existing with musculoskeletal tuberculosis has been about 30 percent. We report here on a case of an otherwise healthy 17-month-old girl, who had tuberculous pyomyositis at the upper arm after the hepatitis A vaccination with no evidence of any coexistent active tuberculosis.