Gait analysis is one aspect of the overall assessment of any patient with a movement disorder. Loss of walking ability is often a major issue to the patient, thus justifying the length of time that should be spent in establishing gait problems and planning re-education. Biomechanical measures of kinematics, kinetics and electromyographical activity are essential to give a complete picture of the specific gait characteristics (Perry 1992; Whittle 1996b). However, observational analysis remains the most commonly used tool in the therapeutic situation (Patla et al. 1987). Reliability of observational analysis is poor (Krebs et al. 1985) and therapists should be encouraged to use objective measures to give a more representative account of the gait pattern. A systematic approach to data collection and recording should be adopted and the key kinematic data of walking including velocity, stride length, base of support and joint angles, should be collected in order to provide a baseline on which to measure clinical effectiveness. Valid outcome measures must be established to evaluate gait effectively to afford therapists the ability to assess their treatment of gait deviations. An understanding of biomechanical terminology is essential to aid the selection of appropriate gait analysis tools and for interpretation of the results.