A field effect transistor inverter-level shifter circuit which accepts TTL input level signals and generates MOS output level signals consists of the series combination of a load device, an enhancement mode transistor, and a depletion mode transistor. The gates of the enhancement and depletion mode transistors are connected to an input terminal. The source of the enhancement transistor is connected to the drain of the depletion transistor. The depletion transistor acts to control the potential of the source of the enhancement transistor so as to allow it to tolerate worse case TTL input potential "0" levels while not becoming more than only weakly biased on.