The long-term transformations of defect structure in GaP, GaAs and InP single crystals treated with pulsed weak magnetic fields are obtained. The treatments were performed in two regimes, namely, single-pulse (tau = 30 ms) and multi-pulse (tau = 1.2 ms) ones, at varying magnitude of magnetic induction. The defect structure transformations were inferred from the radiative recombination spectra in the 0.6-2.5 mu m range at 77-300 K as well as Raman scattering and morphology investigations. A possible mechanism of observed modifications related to the electron spin transformation is discussed. (C) 2011 Elsevier B.V. All rights reserved.