Chest wall hamartoma, commonly known as mesenchymoma, is very rare in infants and usually present at birth. This lesion is a focal overgrowth of normal skeletal elements. Histologically, it is benign. The radiographic appearance is that of a partially mineralized extrapleural mass involving 1 or more ribs. Surgical ablation seems to be the proper treatment and is curative. Cases (9) of this condition presented, including long-term follow-up in 4.