The process of magnetization reversal of Co-rich amorphous wires in circular magnetic field has been studied by Kerr effect. The transverse Kerr loops had features, related to circular domains nucleation and domain wall propagation. A correlation between the switching field and wire length has been found. A remarkable change of the magnetization reversal under the application of axial dc magnetic field was observed. This could be explained by the presence of an interaction between the axial inner core and circular outer shell of Co-rich wires. (C) 2002 American Institute of Physics.