ZnO nanoneedles were synthesized through a simple wet chemical route at room temperature. The diameters of the ZnO nanoneedles tips and roots are about 5 nm and 10 nm, respectively. The sensors fabricated by ZnO nanoneedles exhibited good sensing properties. The sensitivity is 173 against 100 ppm ethanol and the working temperature can be lowered to 150 degrees C. Additionally, a linear dependence of the sensitivity on the ethanol concentration was also observed. These excellent sensing properties can be ascribed to the small size effects, which can be further confirmed by the calculated results. (C) 2009 Published by Elsevier B.V.