In this paper, we report for the first time on the synthesis of ZnO nanocrystallites in conjugated polymer (PPV) nanofibers by the coupling of the in situ/blend methods and electrospinning. These composite nanofibers were characterized by fluorescence microscopy, atomic force microscope (AFM), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), photoluminescence (PL) spectra, Fourier transform infrared (FT-IR) spectroscopy, and X-ray powder diffraction (XRD). In ZnO nanocrystallites/PPV composite nanofibers, ZnO nanocrystallites were distributed uniformly without aggregation. In addition, the incorporation of ZnO nanocrystallites into the conjugated polymer PPV strengthened the photoluminescence (PL) quantum efficiency of the PPV nanofibers. The band structure of the ZnO nanocrystallites/PPV composite nanofibers should be in favor of photoexciton generation and radiation of PPV. These composite nanofibers; with excellent fluorescent property are potentially interesting for many applications such as micro- and nano-optoelectronic devices and systems. (c) 2008 Elsevier Ltd. All rights reserved.