An over voltage protection circuit, especially adapted for the protection of field effect transistor gate dielectric material and other circuit structures against high voltage, high peak current, short duration impulses such as produced by static electricity. The gate of the protected FET is shunted to ground by a lateral bipolar transistor whose collector junction is passivated by a layer of silicon dioxide thinner than the passivation layer at other locations. The silicon dioxide layer is covered by a metallization layer which extends from above the collector junction and makes contact to the emitter and to the substrate. The substrate contact is connected to a source of fixed potential. The collector is connected to the gate of the protected FET.