Abstract: An optimization of electrical characteristics for treatments of tumor or other abnormal cells in culture with sub-microsecond, high-electric field electrical pulses is disclosed. The voltages, pulse widths, and number of pulses are chosen such that the treatment energy is 10-20 J/mL. That is, U=n*?t*V*I/volume is 10-20 J/mL, in which n is the number of pulses, ?t is the duration of each pulse, V is the voltage, I is current, and volume is the area of parallel electrodes times the distance between them. V divided by the distance between the electrodes can be in an effective range of 6 kV/cm to 30 kV/cm, 60 kV/cm, 100 kV/cm, or higher intensities. Rows of needle electrodes, blade electrodes, or other configurations of electrodes can approximate parallel electrodes.