Actinomycosis is chronic, progressive but non-infectious disease characterized by abscess, fistulization and sulfur granules. The major clinical forms of actinomycosis are: cervicofacial, thoracal, abdominal, pelvic and systemic forms. The thoracal form accounts for 15% of all cases and most are localized within lungs. Extrapulmonary cases are extremely rare. Only 7% of all cases of actinomycosis have been diagnosed under the age of ten. In this article, a nineyear- old boy, complaining of pain and mass on the outer face of the chest wall, is discussed together with its rare localization and clinical presentation. Anahtar Kelimeler : Torasik aktinomikoz, göğüs duvarında kitle, thoracal actinomycosis, mass on chest wall.