A contingent valuation survey was conducted in Taiwan to elicit willingness to pay (WTP) to avoid a recurrence of the episode of acute respiratory illness most recently experienced by the respondent. We estimate a model in which willingness to pay depends on the attributes of the illness (duration and number of symptoms, and nature of the illness) and on respondent characteristics (such as income and health history), and allow mitigating behavior to be endogenously determined with willingness to pay.