Here, we describe the detailed structure of an intact murine monoclonal anti-hERG1 molecule and the corresponding anti-hERG1 scFv antibody production, obtained after the isolation of the mAb anti-hERG1 VH and VL. Such scFv has the same 5 specificity of the correspondent whole antibody, and thus it is able to recognize the same anti-hERG1 protein, aberrantly expressed in tumours and other diseases