The neural cell adhesion molecule (NCAM) is expressed by myelinating precursor cells in neonatal mouse spinal cord and by remyelinating cells after chemically induced demyelination in adult mouse. It shows tempting suggestions about its possible involvement in the reparative mechanisms and the remyelination processes that take place in multiple sclerosis (MS). In fact, its levels progressively increase in the cerebrospinal fluid (CSF) of acute MS patients subjected to steroid treatment, paralleling the progressive clinical improvement after the attack. Such an increase is not found in acute MS patients not treated with steroids nor in non-acute patients subjected to the same steroid treatment.