The objective of this study was to determine whether olfactory ensheathing cells (from E18 rat embryos) could myelinate dorsal root ganglion neurites in vitro. By four weeks many of the S100-positive ensheathing cells were Gal-C+ and MBP+ and had begun to myelinate the larger axons, as visualized with the electron microscope. We conclude that olfactory ensheathing cells can form a myelin sheath if given the opportunity to ensheath neurites of a proper size.