A method to estimate water saturation (S.sub.w) of a thin-bedded formation is provided including (a) developing a model of anisotropy of resistivity (R.sub.v/R.sub.h) a function of water saturation (S.sub.wt) for one or more volume fractions (either F.sub.shale or F.sub.sand); (b) measuring the anisotropy of resistivity of the formation; (c) measuring the volume fraction of the formation; (d) correlating anisotropy of resistivity to the measured volume fraction of the formation using the model to estimate the water saturation (total water saturation or sand water saturation) of the formation.