The spreading dynamics of non-Newtonian fluids, in wetting and dewetting modes, plays a key role in numerous applications in particular in coating, adhesive bonding, and printing. The very common case of the shear-thinning behavior has been considered in this study. The wetting dynamics has been studied by depositing sessile drops on glass slides. The dewetting kinetics has been evaluated by measuring the rate of growth of dry zones nucleated in an unstable liquid film formed on Teflon-coated glass slides. The spreading kinetics of a liquid on a rigid substrate is governed by viscous dissipation in the liquid, the capillary driving force being compensated for by the braking force resulting from viscous shearing in the liquid. In the case where the liquid is not Newtonian but shear-thinning or pseudoplastic, a deviation from the classical hydrodynamic theory (Newtonian behavior) for wetting is obviously observed, in particular a slower wetting kinetics corresponding to an apparent increase of the liquid viscosity as the spreading speed decreases. The shape, slightly nonspherical, of shear-thinning drops having a size smaller than the capillary length, is also simply interpreted, observing that the actual viscosity increases from the edge to the center of drops during wetting, near the solid surface. In the dewetting mode no drastic changes are observed when compared with the general behavior of Newtonian liquids. The rate of growth of dry zones nucleated in an unstable liquid film stays constant, as for Newtonian liquids, at: least at the early stages of the growth of dry patches. The proposed adaptation of the hydrodynamic theory is supported by several experimental results concerning the kinetics of spreading in the wetting and dewetting modes. A good agreement is observed between the proposed theory and the results.