Breast masses are very rare in infants and premature telarche due to excessive endogen or exogenous estrogens is the most common presentation during infancy. Myofibroblastoma is a stromal tumor of the breast, occurring especially in elder males. This breast mass has a close relationship between androgen receptors and has not been reported in infants previously. A 10-month old male baby with a left breast mass, which is diagnosed as myofibroblastoma, is discussed to evaluate the clinical features and treatment modalities of breast myofibroblastomas in children.