ZnO thin films were grown on Si(100) and sapphire (001) substrates by an in situ ultraviolet-assisted pulsed laser deposition technique. Using this technique, highly textured ZnO films were grown on Si substrates even at 100 degrees C. Films grown on sapphire (001) at temperatures higher than 400 degrees C, were found to be epitaxial by Rutherford backscattering (RBS) and X-ray pole figure measurements, with [001](ZnO) parallel to [001](sap) and [100](ZnO) parallel to [110](sap). The minimum yield of the channeling RES spectra recorded from films deposited at 550 degrees C was around 2%, while the full width at half maximum of the rocking curve on the (002) diffraction peak was only 0.168 degrees. Such values, characteristic for high quality epitaxial ZnO films, are identical with those previously reported for films grown by conventional pulsed laser deposition at 750-800 degrees C substrate temperatures.