This paper presents light and electron microscopic findings in a case of fibrous hamartoma of infancy. Histological examination revealed different tissue components: irregular trabecular collagen fibers among mature adipose tissue, and mesenchymal cells at the border of fibrocollagenous trabeculae as well as around blood vessels. Ultrastructurally most of the tumor cells represented myofibroblasts. According to the predominance of a distinct cell type, fibrous hamartoma of infancy cannot be regarded as a hamartomatous lesion but should be included in the group of juvenile fibromatoses under the term ‘infantile subcutaneous myofibroblastoma