In the normal dorsal root ganglion (DRG), it has not been vigorously investigated what kind of glial cells proliferate. In this study, we histochemically studied the proliferating glial cells in 6 weeks old male adult rat DRG. Proliferating glial cells were labelled by BrdU and the animals were euthanized 2 hours and 2weeks after BrdU administration. Glial cells were immuno-stained with anti-S100, anti-glutamine synthetase antibodies (pan-glial cell markers), and anti-myelin basic protein antibody (myelin sheath marker), and were defined by their morphology. Two hours after BrdU administration, BrdU was detected in some glial cells enwrapping initial segment of neuronal process which is non-myelinated region. These glial cells were distributed along the neuronal process in longitudinal chain. Each of them covered single neuronal process like as myelianting Schwann cells. This type of glial cells (New cell) corresponded with periaxonic satellite glia by Pannese in 1960. Especially, BrdU positive New cells were often found in the vicinity of distal end of the initial segment of neuronal process which is a zone where myelinating Schwann cell appear. BrdU was also observed in so-called satellite glia covering neuronal soma at 2 hours and 2 weeks after BrdU administration. The myelinating Schwann cells were BrdU negative up to 1 week after BrdU administration however some myelinating Schwann cells close to New cell were BrdU positive at 2 weeks after BrdU administration. Further, myelin sheathes of most proximal Schwann cells were often thinner than others, indicating newly forming myelin sheathes. These results showed that New cell proliferated at distal end of initial segment, and differentiated into myelinating Schwann cell in the normal young adult rat.