Polypyrrole (PPy) films processed from solution have been used as semi-transparent anodes in polymer light-emitting diodes. An external quantum efficiency of 0.5% was achieved with poly(2-methoxy,5-(2'-ethyl-hexyloxy)-1,4-phenylene-vinylene) (MEH-PPV) as the luminescent polymer. The hole-injection potential barrier between PPy and MEH-PPV, as determined by Fowler-Nordheim analysis, is phi approximate to 0.23 eV.