The effects of neutron damage on the red and green light output at 300 °K of GaP lightemitting diodes have been examined. The results indicate that the diodes are not sensitive to neutron irradiation in those voltage regions where the radiative current is due to spacecharge recombination in the depletion layer. As a consequence of this, it is shown that the response of the diodes to neutron irradiation can be used to elucidate the radiative currentflow mechanisms in these devices.