A technique for making self-assembled electrospun (E-spun) nanofiber yarns frorn poly(acrylonitrile) in a single step is described. The process involved formation of the nanofiber yarn directly within the electro-spinning zone and its removal before it can reach the counter-electrode. The yarn is presumably formed due to splitting of the main jet into numerous nanojets and their reassembly, into a single entity midway between the two electrodes. The process was found to occur at a particular field strength, which varied considerably, with the concentration of the polymer dope. The gross morphology of yarns and the alignment of nanofibers in the yarn were evaluated by scanning electron microscopy (SEM). The rationale behind the formation of the yarn like structure has been explained. (C) 2008 Wiley Periodicals, Inc.