Chest wall mesenchymal hamartoma is an extremely rare benign tumor. Approximately 80 cases have been reported in the literature. Most tumors are manifested at birth with a painless palpable mass of the chest wall, usually unilateral. Respiratory symptoms result from extrinsic compression of the pulmonary parenchyma, and the severity of the symptoms will depend on the size and location of the lesion. Imaging features are characteristic, but definitive diagnosis is histological. Herein, a case is described of a four month old infant with diagnosis of chest wall mesenchymal hamartoma, manifested at birth. Different treatment options are described, including expectations from tumor management, the possibility of spontaneous regression, and the morbidity associated with the surgical option.