A prospective observational study of the performance of patients enrolled in an individually customized program of habituation and balance rehabilitation physical therapy was conducted from January 1988 to January 1990. Patients ranged in age from 20 to 89 years, with a wide variety of diagnoses. Two global outcome measures--posttherapy symptom response score and pretherapy and posttherapy disability score--were developed and used to judge overall patient performance. In addition, two specific indicators--one for balance performance (dynamic posturography) and one for sensitivity to rapid head movements (motion sensitivity quotient)--were used to measure performance in these two areas. Results indicate statistically significant changes before versus after therapy for both specific measures, and 80% to 85% of the patients showed a reduction in symptoms and disability score following therapy. Analysis of variance and multiple regression analysis indicate that nature of symptoms, pretherapy disability level, history of head injury, and results on dynamic posturography were the variables most predictive of therapy outcome, while age and duration of symptoms made no difference. Other variables, such as medications and site of lesion, were found to affect the length of therapy but not the outcome.