A case report of Dupuytren's contracture illustrates the functional and light and electron microscopic characteristics of the myofibroblast. The myofibroblast is now associated with an increasing number of diseases, and is believed to be a morphologic and functional variant of the fibroblast, which shows changes typical of smooth-muscle cells. Its presence may be suspected by light microscopy, but its ultrastructure is characteristic. Its distinctive electron microscopic features are a fibrillar system in the cytoplasm similar to that of a smooth muscle, nuclear deformations indicative of contraction, and surface membrane differentiations that provide attachment to neighboring cells and stroma.