In order to investigate the behavior for very high current densities of polymer resistors on flexible substrates, a pulsed measurement technique was applied. The analytical test technique of Transmission Line Pulsing (TLP) allows, on the basis of square pulses, the in-situ monitoring of the voltages and currents at the Device Under Test (DUT) during pulsing and helps to gain fundamental insights into the electrical behavior at higher current densities. The influence of the pulse amplitude on the current-voltage behavior was investigated on thick film carbon-based polymer resistors on flexible foil, like polyimide (Upilex). The resistance change due to an applied high voltage pulse stress is a measure of the ESD susceptibility of the thick film polymer resistors. The measurements show that the thick film flexible, carbon based resistors on Upilex foil are susceptible to high energy pulses. Parametric failure or catastrophic damage can occur.