Erbium doped fiber EDF has been irradiated by a neutron dose up to 200 krad. The Gain of the C-band EDFA has been investigated at different distances from Am-241/Be-9 neutron source. An analytically model based on the classical equation of propagation was developed to perform an accurate prediction of the effects of the radiation on the erbium doped fiber amplifier, EDFA. The EDFA was exposed to a neutron beam emitted from the source for 24 hours at each distance. The gain of EDF deteriorates after being irradiated by a neutron dose. The gain of irradiated EDFA comes down to 14 dB at radiation dose of 200 Gy. The results obtained by the present model and the measured ones are in good agreement. (c) 2013 Elsevier B.V. All rights reserved.