A systematic orientation analysis of individual electrospun polyethylene (PE) nanofibers was performed by transmission electron microscopy (TEM). PE nanofibers with a wide diameter distribution, ranging from 150 nm to several micrometers, and a variety of morphologies, including cylindrical, beaded- and ribbon-like fibers, were produced by the high-temperature solution electrospinning. In each fiber, crystalline orientation and its morphology were investigated by TEM. In the cylindrical fibers, development of fiber structure was strongly related to the fiber diameter. Depending on the diameter, three different structural models based on 1) the random-oriented crystalline structure, 2) the shish-kebab structure, and 3) the fibrillar structure composed of extended-chain crystals were proposed. In addition, orientation analysis of beaded fibers and that of ribbon-like fibers was also performed. (C) 2010 Elsevier Ltd. All rights reserved.