The results of experimental study of radiation resistance of GaAs-based solar cells are presented. The solar cells were irradiated by 1 MeV electrons at room temperature with the fluence up to 4 x 1016 electrons cm(-2). The radiation influence on the dark current and short-circuit current under illumination was investigated both experimentally and theoretically. It is shown that the radiation-produced electron traps E5 and hole traps HI are responsible for irradiation-induced degradation of such solar cells. The radiation tolerance of the basic parameters (the short-circuit current, the output power) of GaAs solar cells is primarily determined by the radiation damage in p-regions. (C) 2008 Elsevier B.V. All rights reserved.