This research considers the determination of the preservation value of Gaz trees on the banks of Fahliyan River located in Rostam and Mamasani region and measures individuals willingness to pay (WTP) for the preservation of these trees using a contingent valuation method. A Logit model was used for measuring individuals WTP and the model indicators were estimated through maximum likelihood (ML). The results showed that 78.50/0 of individuals were willing to pay for preservation of these trees. The average amount of WTP for the annual preservation value of Gaz trees were calculated at 5540 Rials per month for each household. The annual preservation value was estimated 1650 million RLs. This value is an acceptable justification for politicians and decision makers to show more support to the quality and quantity of Gaz trees.