This study focused on fabrication and characterization of porous core/sheath structured composite nanofibers with a core of blended salicylic acid (SA) and poly(ethylene glycol) (PEG) and a sheath of poly(lactic acid) (PLA) using a dual-capillary electrospinning system. Results of water contact angle measurements, field-emission scanning electron microscopy, and transmission electron microscopy indicated that feed rates of the core and sheath strongly affect the stability of the core/sheath structure and porous density of the composite nanofibers obtained, significantly influencing their SA release characteristics. At a lower ratio of feed rates of the core and the sheath, better stable core/sheath structures of nanofibers with higher porous density on the surface were formed resulting in a sustained release of SA over 5 days. Non-porous fibers showed a lower amount of drug release because the drug was embedded inside the core layer of the non-porous sheath layer. SA release from porous core/sheath nanofibers was described based on a one-dimensional Fickian diffusion mechanism, indicating that drug diffusion is a predominant factor in drug release. A cytotoxicity test suggested that the porous core/sheath nanofibers are non-toxic and support cell attachment. Therefore, this fiber mat may find application in the design of wound-healing patches with long-term activity. (C) 2012 Elsevier B.V. All rights reserved.