This paper reviews the literature relating to foot orthoses, in particular foot orthoses that attempt to alter biomechanical function. Whilst few well-controlled studies have been performed, the findings from the available literature are generally positive. The authors provide an overview of this literature and then summarise the findings. The literature is categorised into six research outcome areas: (i) patient satisfaction, (ii) pain and deformity, (iii) plantar pressures, (iv) position and motion, (v) muscle activity, and (vi) oxygen consumption. In addition, the difficulties associated with researching foot orthoses are discussed.