The Las Tazas Complex is a ferromagnetic I-type granitoid that crops out in the Coastal Cordillera of northern Chile. Magnetic susceptibility patterns across the complex are controlled by modal magnetite contents, rather than overall mineralogy, resulting in an ambiguous correlation between susceptibility magnitude variation and lithological zoning. There is a good correlation between plagioclase magmatic fabric orientations and magnetic fabric orientation, demonstrating that anisotropy of magnetic susceptibility (AMS) measurements can accurately characterize magmatic fabric patterns in Cordilleran I-type granitoids. However, there is no simple quantitative relationship between magmatic and magnetic fabric intensities. The magmatic and magnetic fabrics share a similar character, and it is clear that AMS fabrics are strongly influenced by the dominant plagioclase fabric across the Las Tazas Complex but cannot be directly equated in quantitative strain analysis. ¿ 1998 American Geophysical Union