The process of remyelination in the superior cerebellar peduncles of mice following demyelination with Cuprizone was studied immunohistochemically using antisera to myelin basic protein (MBP) and myelin-associated glycoprotein (MAG). Demyelination occurred after formation of myelinic vacuoles and resulted in almost complete loss of demonstrable MBP and MAG from the peduncle. Prior to the onset of remyelination, oligodendrocytes with cytoplasmic staining for both proteins appeared in the peduncle. These cells were then associated with remyelinating axons. The axons were remyelinated in clusters until the MBP and the MAG in the whole peduncle were reconstituted, although the axon sheaths were thinner than those in normal animals. The results show that the immunohistochemical distribution of MBP and MAG in remyelinating axons resembles that in normal axons, and that the expression of myelin proteins in oligodendrocytes during remyelination reverts to that seen during normal development.