Abstract: The behavior of the electron spin relaxation time in bulk GaAs layers doped with Mn was studied experimentally. We investigated the dependence of the degree of circular polarization of photoluminescence in transverse and longitudinal magnetic fields. An increase in the relaxation time of the electron spin is found from 25 ns at low pumping power to 400 ns at the threshold pumping power. The effect of resonant cooling of the nuclear spin system by optically-oriented electron spins is demonstrated.