A scanning tunneling microscope was used to generate electroluminescence (EL) from thin films of the conjugated polymer poly(1,3-phenylenevinylene-co-2,5-dioctyloxy-1,4-phenylenevinylene). This allowed the spatial distribution of EL to be mapped across the film, and also measurements of local EL emission spectra to be recorded. It was observed that both the emission spectra and their intensity are highly nonuniform on length scales ≳ 2 nm. This is important in the context of light emitting diodes since it indicates that control of nanostructure can greatly improve device performance. © 1997 American Institute of Physics.