Pores in rocks synthesized at deep crustal and upper mantle conditions (1.0--1.5 GPa and 800¿--1400¿C) become aligned parallel to imposed temperature gradients. The extent of pore channelization varies with lithology and is strongest for calcite + quartz + wollastonite with a mixed H2O-CO2 fluid. Channelization of H2O fluids is strong but decreases in quartz, fluorite, and then olivine, and is weak for calcite + H2O. Melt-filled pores in dunite also become aligned with an imposed gradient in temperature. Channelization of pores may be rare in most natural settings because of the relatively low temperature gradients. Pores may, however, become aligned in rocks subjected to gradients in fluid composition alone (e.g., XCO2). Compared with rocks characterized by uniform pore geometry, channelized rocks, whether experimental or natural, may be subject to directionalized flow and to establishment of fluid connectivity at a relatively low fluid or melt fraction.