The design and production of drug-loaded nanofiber based materials produced by electrospinning is of interest for use in innovative drug delivery systems. In the present study, ultra-fine fiber mats of thermoplastic polyurethane (TPU) containing naproxen (NAP) were successfully prepared by electrospinning from 8 and 10% (w/w) TPU solutions. The amount of NAP in the solutions was 10 and 20% based on the weight of TPU. The collection period of the drug-loaded electrospun TPU fibers was 5, 10 and 20 h, and they were characterized by FTIR, DSC and TGA analysis. The morphology of the NAP-loaded electrospun TPU fiber mats was smooth, and the average diameters of these fibers varied between 523.66 and 723.50 nm. The release characteristics of these fiber mats were determined by the total immersion method in the phosphate buffer solution at 37 degrees C. It was observed that the collection period in terms of the mat thickness played a major role in the release rate of NAP from the electrospun TPU mats. (C) 2016 Elsevier B.V. All rights reserved.