The long-term transformations of photoluminescence of GaP, GaAs and InP single crystals treated with pulsed weak magnetic fields are obtained. The treatments were performed in two regimes, namely, single-pulse (<$E tau> = 30 ms) and multi-pulse (<$E tau> = 1,2 ms) ones, at varying magnitudes of magnetic induction. The defect structure transformations were inferred from the radiative recombination spectra in the 0,6 - 2,5 <$E mu>m at 77 K. A possible mechanism of observed modifications related to the electron spin transformation is discussed.