Novel hG-CSF polypeptide derivatives having an amino acid sequence derived from the amino acid sequence of the human granulocyte colony stimulating factor polypeptide by substitution of at least one amino acid by a different amino acid and/or deletion of at least one amino acid, recombinant plasmids containing a DNA fragment insert coding for any of these hG-CSF polypeptide derivatives, microorganisms carrying one of such plasmids, methods of producing the hG-CSF polypeptide derivatives using the microorganisms, a monoclonal antibody binding to the hG-CSF polypeptide derivative, and chemically modified hG-CSF or derivatives thereof are disclosed.