The pore fabric of sandstones is studied by impregnating porous samples with a magnetic suspension (ferrofluid) and subsequently measuring their anisotropy of magnetic susceptibility (AMS). Similar to the use of natural AMS for estimation of grain fabric, we determine average orientation and shape anisotropy of pore bodies in three dimensions. This new approach overcomes restrictions of previous methods of pore structure characterization. The interpretation of AMS in terms of pore fabric anisotropy is tested by comparison with pore shape observed in thin section. An image analytical technique is used to derive statistically the elongation direction of digitized pore cross sections. By computing the two-dimensional autocorrelation function we obtain section ellipses reflecting average pore shape and orientation. Combination of ellipses of three mutually perpendicular images leads to fabric ellipsoids comparable to AMS. Comparison of the two anisotropies shows a close correspondence between the principal axis directions of AMS and fabric ellipsoids. Owing to the bedded nature of the samples, the ellipsoids are of oblate shape with minimum axes perpendicular to bedding. However, even small anisotropies within the bedding plane can be detected successfully. Axial ratios of AMS and fabric ellipsoids correlate closely if rock sample AMS is corrected for pore directional scattering. The method represents a powerful tool to analyze pore fabric of sedimentary rocks and to study its effects on petrophysical properties. ¿ American Geophysical Union 1993