We have measured the resistivities p of two ≈ 3000-A thick RuOz films between 0.3 and 10 K. As the temperature T is lowered below 10 K, a resistivity rise varying with the square root of temperature is observed. This p behavior with T is well ascribed to electron-electron interaction effects in a three-dimensional disordered metal. A quantitative comparison of the experiment with recent electron-structure calculations for this material is performed.