Subjective, behavioral, cardiovascular and neuroendocrine responses were intensively monitored in two height phobics over a full course of exposure therapy and at follow-up. Both subjects showed rising cortisol responses and stable, non-extinguishing norepinephrine responses to height exposure over the course of treatment, while improvement occurred in subjective and behavioral response systems. They had differing heart rate responses. Despite desynchrony amongst anxiety response systems and within the physiological 'system' at treatment conclusion, both subjects had successful outcomes which were preserved at follow-up. Implications for the measurement of the 'physiological response system' in behavioral research are discussed.