Myelinating Schwann cells are particularly susceptible to defects in endosomal trafficking. TSG101 is a component of the endosomal trafficking machinery that mediates the sorting of ubiquitinated receptors into multivesicular bodies. We previously demonstrated that deleting Tsg101 from mouse oligodendrocytes in the central nervous system causes rapid onset de/dys-myelination and vacuolation of white matter, suggesting an important role for TSG101-dependent trafficking in myelination. Here, we show that TSG101 is also required for normal myelination in the peripheral nervous system.