Disclosed is the use of a composition comprising a single chain polypeptide that binds human CD20 in the manufacture of a medicament for treating an individual having rheumatoid arthritis, wherein the single chain polypeptide that binds human CD20 comprises from amino to carboxy terminus: a human CD20-specific single chain Fv (scFv), a human immunoglobulin hinge region, and a truncated human immunoglobulin constant region； and wherein the composition is administered (1) as a therapeutically effective single dose, or (2) as a therapeutically effective single dose followed by a maintenance treatment in about three months to about two years after the initial single dose.
