A computer program was developed to help diagnose orthopedic gait disorders. Designing and implementing the program, as well as the program's method of operation are described. The main features of the program include: a knowledge base of facts about orthopedic gait, organized into premise-conclusion pairs; a goal-directed reasoning chain that causally relates the facts; and a symbolic structure that allows limited English discourse between the user and the computer. Results of the project indicate that the complex area of gait analysis does lend itself to diagnosis by computer and that this prototype has potential as an aid to physical therapists in the classroom and in the clinic.