Abstract: A biopsy method and apparatus for determining and locating the presence or absence of a neoplastic and other disease condition within a human or animal subject by detecting during a test period the respective electrical potentials of the electromagnetic field present in the subject between each of a plurality of measurement locations in the area of the neoplasm and at least one reference location while a combination biopsy instrument and electrode is inserted into the subject at the location of suspected neoplasm. Electrical potential differences are compared during this period to obtain relationships therebetween which are indicative of either the presence or absence of neoplastic tissue. Once the neoplastic tissue is located and identified, the biopsy instrument is manipulated to remove a tissue sample for further study.