The influence of pore fluids in the tectonics of modern subduction zones has been argued by only a few authors and is mentioned only casually in much of the earth science literature on subduction because of the difficulty of obtaining data on pore pressure in modern trench environments. Limiting values of physical properties can be derived along modern subduction zones where DSDP and other sampling recovered deep materials. We use two equations that bracket a conservative situation and present a simplified case where only vertical loads are considered to obtain simple estimates of pore pressure along the Aleutian, Oregon-Washington, Japan, Nankai, Middle America and Barbados subduction zones. The calculations indicate that sufficiently elevated pore pressure can d velop early in the subduction process, making possible low shear strengths and low friction across faults in the front of some subduction zones. Very low friction is a convenient way to achieve the high degree of decoupling required in explanations of subduction related tectonic processes.