An investigation has been made of the dependence of the magnetic losses on the frequency f(20 ≤ f ≤ 1000 Hz) and induction Bm(0.1 ≤ Bm 0.75 T) of the amorphous, rapidly quenched alloy Fe81Si4B13C2 at 300 and 77 K. There is anomalous growth of the magnetic losses per cycles as the frequency decreases from 200 to 20 Hz. This can be interpreted as a consequence of a magnetic aftereffect, which leads to anomalous growth of the domain wall velocity due to the appearance of correlated Barkhausen jumps.