Foot orthoses are routinely used in clinical practice to redistribute pressure at the shoe-foot interface, although there is very little scientific evidence to support the efficacy of their use. In this study, the FSCAN sensor (an ultrathin in-shoe transducer) was used to determine the efficacy of pressure redistribution with a Plastizote, Spenco, cork, and a plastic foot orthosis as compared with control (no orthosis). Measurement variations of up to 18% occurred between sensors, and changes in stance time of up to 5% occurred between the orthoses and the control conditions. In spite of these potentially confounding variables, statistically significant differences in peak pressure between the orthotic types and the control condition (range, 9-146%) were noted. We conclude that Plastizote, cork, and plastic foot orthoses can be beneficial in relieving pressure in certain regions of the shoe-foot interface, but that they may do so at the cost of increasing pressure in other areas of the plantar surface.