The subject invention relates to isolated proteins, particularly monoclonal antibodies, which bind to the Nogo-66 receptor. Specifically, these antibodies have the ability to inhibit the binding of the natural ligand of the Nogo-66 receptor and neutralize the Nogo-66 receptor. These antibodies or portions thereof of the invention are useful for detecting NgR and for inhibiting NgR activity, for example in a human suffering from a disorder in which NgR or Nogo-66 activity is detrimental.