A study of the giant magnetoimpedance phenomenon and magnetic behavior of soft amorphous magnetic Fe80B10Si10 y Fe78B13Si9 is presented. These materials were produced using the melt spinning technique in form of ribbons. The magnetoimpedance in above ribbons was measured, in frecuency from 25KHz to 20 MHz, in magnetic field between –80 to 80 Oe at room temperature. The magnetic behavior was explored, from –0.6 to 0.6 kOe at room temperature using a Vibrating Sample Magnetometer. The influence of boron content on magnetic properties of above ribbons is discussed.