In this paper, it is proposed one method to recode protest responses applicable to the simple dichotomous format valuation question made to visitors to natural environment in contingent valuation studies. Those respondents that give a protest response but have a travel cost greater than the bid proposed in the valuation question are recoded as an affirmative answer to the proposed payment. The economic justification lies in the minimum willingness to pay for enjoying the environment that travel cost reveals, while valuation question tries to obtain information about respondent maximum willingness to pay. Recoding allows to recover information and to improve estimates, accuracy. It also avoids computational complexity associated with sample selection models used to avoid biases derived from excluding protest responses.