The present invention relates to improved Nanobodies~ against Tumor NecrosisFactor-alpha (TNF-alpha), as well as to polypeptides comprising or essentiallyconsisting of one or more of such Nanobodies. The invention also relates tonucleic acids encoding such Nanobodies and polypeptides； to methods forpreparing such Nanobodies and polypeptides； to host cells expressing orcapable of expressing such Nanobodies or polypeptides； to compositionscomprising such Nanobodies, polypeptides, nucleic acids or host cells； and touses of such Nanobodies, such polypeptides, such nucleic acids, such hostcells or such compositions, in particular for prophylactic, therapeutic ordiagnostic purposes, such as the prophylactic, therapeutic or diagnosticpurposes.
