Abstract: The present invention relates to a particularly advantageous antibody, antibody fragment or derivative thereof, which specifically binds to/interacts with at least one epitope of the extracellular or intracellular domain or the mammalian EAG1 ion channel and to nucleic acid molecules encoding these anti-EAG1 antibodies, antibody fragments or derivatives and to vectors comprising such nucleic acid molecules. The invention additionally relates to methods for the preparation of such anti-EAG1 antibodies, antibody fragments or derivatives thereof, pharmaceutical compositions comprising these antibodies, antibody fragments or derivatives, and methods of using the antibodies, antibody fragments or derivatives or the compositions for a variety of purposes, such as diagnosing disease, treating disease, assessing for the presence of EAG1-expressing cells, or blocking EAG1 function in cells.