The magnetoresistive behavior of granular thin films prepared by Fe and Co implantation in Ag thin films is reported. Ag thin films (similar to 2000 Angstrom) were deposited by evaporation or laser ablation onto Si and SiO2 substrates and implanted with Fe or Co at fluence up to 10(17) at.%/cm(2). The magnetoresistive response obtained after implantation was found to increase with the implanted fluence. An increase of the magnetoresistive response by a factor of 3-4 can be achieved after annealing the films in a conventional furnace at 620 K under vacuum. The best value of magnetoresistance obtained so far is 9% at 10 K and 1.5% at room temperature for a film implanted with Co at a fluence of 8X10(16) at. %/cm(2) and annealed at 620 K.