Rutile-phase TiO2 thin films have been epitaxially grown on GaAs(100) substrates at 700 degreesC under 5 Pa oxygen ambient pressure. and at room temperature (30 degreesC) and 5x10(-4) Pa base vacuum by KrF pulsed excimer laser deposition. The [110]-oriented TiO2 films were composed of two types of domains perpendicular to each other in the plane. From atomic force microscopy analysis, the epitaxial films had a surface with roughness less than 7 nm in root-mean-square.