The monoclinic form of crystal in the room temperature-drawn high density polyethylene has been examined by Infra-red spectroserny and X-ray diffraction. The results show that the monoclinic form of crystal still exists in the specimens drawn at ligh fate even up 8.5 mm/s. It gives direct support to the peterlin's model for the mechanism of plastic elongation of semicry-stalline polymers.