This paper describes the effect of electron irradiation and thermal annealing on LPE AlGaAs/GaAs heterojunction solar cells with various p/n junction depths. The electron irradiation experiments were performed with energy of 3 MeV, fluences ranging from 1 x 10(14) to 5 x 10(15) e/cm(2). The results obtained demonstrate that the irradiation-induced degradation of performances of the cells is mainly in the short circuit current and could be mostly recovered by annealing at 260 degrees C for 30 min. Four electron traps, E-c - 0.24 eV, E-c -0.41 eV, E-c - 0.51 eV, E-c - 0.59 eV, were found by DLTS analysis, only two shallow levels of which could be removed by the annealing.