This study shows that electrospinning nanofibers onto single microfibers allows for careful tailoring of material properties that may suit a wide variety of applications. The nanofiber-coated microfibers are created by electrospinning nanofibers alongside a microfiber toward a collector that rotates around the microfiber. This force the nanofibers to be collected around the microfiber, creating a hierarchical structure that can be modified at nano scale. In this study, control of nanofiber diameters, nanofiber alignment, and nanofiber loading was evaluated. It was seen that varying polymer concentration affected the nanofiber diameters, collecting the nanofiber-coated microfibers at different speeds changed the degree of alignment of the nanofibers and that changing the polymer feeding rate affected the loading density of the nanofibers collected. The carefully designed nanofiber-coated microfibers have great potential in creation of highly porous materials with tailored properties down to nano scale. © 2010 Wiley Periodicals, Inc.