Vertically aligned ZnO nanowires have been prepared, and intense electroluminescence (EL) has been observed with holes injected into the nanowires from p-type ZnO prepared via a high pressure high temperature route. The emission can be attributed to the radiative recombination between the electrons in the nanowires and the injected holes, and the power of the EL can reach about 10 μW when the injection current is 20 mA. The intense emission is believed to be resulted from both the relatively high quality of the nanowires and injection of the holes from the p-type ZnO.