The magnetoresistive behavior of granular thin films prepared by Fe and Co implantation in Ag thin films is reported. Ag thin films (∼2000Å) were implanted with Fe or Co at fluences up to 8×1016 at./cm2. The magnetoresistive response obtained after implantation was found to increase with the implanted fluence. A further increase by a factor of 3–4 can be achieved annealing the films in a conventional furnace at 620 K under vacuum. The best value of the magnetoresistance obtained so far is 9% at 10 K for a film implanted with Co at a fluence of 8×1016 at./cm2.