Mammary-type myofibroblastoma of the soft tissue is a benign mesenchymal tumor, and it is a recently established clinical entity. We report a case of myofibroblastoma of the chest wall with a prominent epithelioid feature, that occurred in a 12-year old female. Although the lesion occurred in the breast area, there was no breast parenchyma in or around the mass, which favored soft tissue of the chest wall origin. The tumor was immunohistochemically identical to the mammary-type myofibroblastoma with diffuse and strong positivity against CD34 and desmin. The myoepithelial differentiation of the tumor was further supported by the electron microscopic analysis. This case indicates that mammary-type myofibroblastoma can occur in a young girl. The mammary-type myofibroblastoma should be considered a differential diagnosis, among epithelioid soft tissue neoplasms in the chest wall when the proper immunohistochemical work-up is done.