Ag/Co multilayers (MLs) showing the giant magnetoresistance (GMR) were prepared by electron beam evaporation in UHV at room temperatures onto Si/SiO2 substrates. The samples were thermally processed by excimer laser irradiation at the fluences F = 0.1, 0.15 and 0.2 J cm(-2) and number of pulses between 1 and 200. The samples were analyzed by X-ray diffraction (XRD) and grazing incidence (GI)XRD. The electrical resistance R(H) was measured up to 50 kOe with magnetic field perpendicular or parallel to the film plane and with current in plane of the multilayers at 4.2 K. Two different types of MLs were studied. In one of them [(2 nm Ag/l nm Co) x 5], Ag layers melt under laser irradiation according to our numerical computations and the change of GMR is non-systematic. In the other MLs [(6 nm Ag/l nm Co)x 5] the Ag and Co layers don't melt and the GMR increase vs. deposited laser energy is almost systematic. This effect is ascribed to the transformation of continuous Co layer into discontinuous one with larger inter-facial area between non-magnetic and magnetic components in the ML.