Highly conductive metallic oxide thin films ofSrRuO3with single crystalline quality have been grown on (001)SrTiO3by using pulsed laser deposition. The films have a[00l] orientation with an in-plane relationship of[110]SrRuO3 // [100]SrTiO3.They have excellent metallic behavior with room temperature resistivity of∼310&mgr;&OHgr; cm and a residual resistance ratio of about 7 at 4.2 K, the largest reported to date. A clear ferromagnetic transition at∼147 K was detected by resistivity and magnetic measurements. However, the transition becomes blurred as the density-of-point defects increases in the films following a 400 keV proton irradiation with an accumulative dose up to∼6.0×1016 ions/cm2.©1997 American Institute of Physics.