In this paper, we present the giant-magneto-impedance (GMI) effect in a microfabricated closed Permalloy core which surrounds a copper excitation rod. We measured a 90% change in the inductance value of the device for a sinusoidal excitation at 500 kHz in a 4.5mT range. The change in the device resistance is negligible for excitation frequencies below 1 MHz, and goes above 14% for 30 MHz excitation. Magnetic hysteresis of the device inductance is studied and improved by applying periodic “degauss” pulses during measurement, instead of increasing the amplitude of the excitation current or using traditional annealing processes.