HDPE monofilaments were extruded with different extruders. After solidification, drawn and undrawn monofilaments (draw ratio 7:1) irradiated with 10 MeV electron beams in air at room temperature at 25, 50, 75, 100 and 125 kGy dose ranges. HDPE crosslinking was studied on the basis of gel content measurement. The fibers examined by differential scanning calorimetry (DSC) and mechanical properties. It has been shown that gel fraction increased with irradiation dose up to 75 kGy and showed a significant increase with draw ratio but in higher doses remained without considerable changes. Melting temperature of drawn fiber increased with raising irradiation dose but decreased in undrawn sample. Also bimodal endotherm was observed for drawn polyethylene irradiated in air. The changes in melting temperature and appearance of bimodal endotherm are related to the radiation chemistry of polyethylene in the presence of oxygen and interlamellar interactions. Heat of fusion and degree of crystallinity slightly increased for undrawn and drawn samples but, heat of crystallization was reduced by increasing of irradiation dose due to crosslinking. Tensile properties decreased because of oxidative degradation. Elongation at yield for undrawn samples and elongation at break for drawn types increased with irradiation dose up to 125 kGy and no significant changes were seen in Young modulus by increasing the irradiation dose. Decreasing tensile properties occurs because of oxidative degradation caused by present oxygen molecules during the irradiation in the process. Elongation at break and Elongation at yield increased for all samples. Young modulus was not significantly changed by increasing the irradiation dose. Keywords: polyethylene fiber, electron beam, crosslinking, draw ratio.