We fabricated electrospun polymer nanofiber waveguides composed of a poly(methyl methacrylate) nanofiber core doped with an organic dye and a Cytop cladding. Photoluminescence (PL) spectra are measured at the end face of individual cores with increasing distance (d) between the end face and the point of irradiation by the excitation laser beam. PL intensity at a wavelength of 700 nm decreases according to the relationship similar to exp(-alpha d) where the loss coefficient (alpha) is 17-75 cm(-1). The value of alpha is lower in waveguides with cladding than in those without. Reabsorption of emission by the dye is also evaluated to be 3.9 cm(-1). We confirm that the propagation loss in the waveguide results mainly from the losses inherent to the PMMA fiber itself. (C) 2013 Elsevier B.V. All rights reserved.