Monoclonal antibodies are of growing interest as treatment options for 
immune-mediated diseases in neurology. As our knowledge of immunological 
principals increases, we learn to modulate specifically mechanisms of 
pathogenesis by the use of monoclonal antibodies. It is clearly desirable to 
improve efficacy in disease treatment without increasing toxicity by using drugs 
with more specific modes of action. Natalizumab was the first monoclonal 
antibody approved in the field of neurology for treatment of relapsing remitting 
multiple sclerosis (MS). Several other monoclonal antibodies are currently under 
investigation. Alemtuzumab, a monoclonal antibody targeting CD52, is a highly 
promising agent currently being studied in two phase III clinical trials. In 
this review, data from the recently published phase II clinical trial in the 
treatment of early relapsing remitting MS is summarized and analyzed in light of 
the development of alemtuzumab for MS and its potential role in treating this 
disease is discussed.