In this study we explore the feasibility of using of islands-in-the-sea (I/S) fibers in the spunbond process to produce relatively high strength micro- and nanofiber webs. The relationships between the number of islands, percent polymer composition, and the fiber and fabric properties are reported. Nylon 6 (N6) and poly (lactic) acid (PLA) were used as the islands and sea polymers, respectively. Micro-and nanofibers were obtained by dissolving PLA polymer from the final spunbond nonwovens. The fibers with 25% N6 showed a decrease in fiber diameter from 1.3 to 0.36 mu m (micron) when the number of islands was increased from 36 to 360. The diameter of fibers with 75% N6 showed a decline from 2.3 to 0.5 mu m for the same range. Hydroentangling was found to be the preferred method of bonding of the I/S structures; the bonded structures were able to withstand postprocessing steps required for dissolving of the sea from the resulting nonwovens. Hydroentanged micro- and nanofiber based nonwovens demonstrated high tensile and tear properties, which were insensitive to the N6 fiber size and its mechanical properties. Bonding efficiency and web uniformity were found to be dominant factors influencing the fabric performance. Overall, our study demonstrated that the I/S configuration is a promising technique for high speed and high throughput production of strong and light weight nonwovens comprised of micro- and nanofibers. (c) 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3434-3442, 2007.