Structural changes accompanying the isothermal annealing of the metallic glass Fe18 Co60 Si9 Β 13 were investigated by X-ray diffraction, positron annihilation as well as by electrical resistivity and the Hall resistivity measurements. It has been found out that at the temperature of 673 K the complete crystallization did not occur, but only a few nuclei of the α-Fe phase, which did not grow, were formed.