We present a simple approach for encapsulating self-assembled iron-platinum (FePt) magnetic nanoparticles in poly(F-caprolactone) (PCL) nanofibers by coaxial electrospinning. Both TEM observation and XPS surface analysis confirmed that the 4-nm FePt nanoparticles were completely encapsulated within the PCL nanofibers. The encapsulated array of the discrete FePt nanoparticles can reach as long as 3000 nm along the fiber axis. Assisted by electrostatic interactions, the FePt/PCL composite nanofibers were readily patterned forming a uniaxial alignment over a large area. The magnetic behavior of the FePt/PCL nanofibers was preliminary studied. (c) 2005 Elsevier B.V. All rights reserved.