A human antibody or an antigen-binding fragment which binds human IL-6 receptor (hIL-6R) with a K.sub.D of about 500 pM or less and blocks IL-6 activity with an IC.sub.50 of 200 pM or less. In preferred embodiments, the antibody the antibody or antigen-binding fragment binds hIL-6R with an affinity at least 2-fold higher relative to its binding monkey IL-6R.