In a method for localizing at least one focal lesion in a biological tissue section, the lesion exhibiting an electrical property different from the tissue section, and the electrical property in the tissue section being essentially constant, a sequence of electrical excitation signals having different frequency is supplied to the tissue section, electrical response signals are measured at a number of measuring locations on the surface of the tissue section that occur due to the excitation signals, electrical admittance data are determined from the response signals dependent on the location on the surface, a maximum of the admittance data and the appertaining position of the maximum on the surface are determined, and a depth position of the lesion under the position of the maximum is determined dependent on the position of the maximum.