Zataria multiflora Boiss (Lamiaceae) commonly grows in Iran is a popular medicinal plant with various pharmacological activities mentioned in traditional Iranian medicine and modern phytotherapy. This study was designed to evaluate the chemical composition and scolicidal effects of Z. multiflora essential oil on the protoscoleces of hydatid cysts on an in vitro model. The components of the Z. multiflora essential oil were identified by GC/MS analysis. Protoscoleces were aseptically aspirated from the livers of naturally infected sheep. Various concentrations of essential oil, thymol and carvacrol were used for 5â30 minutes. Eosin exclusion test was used to determine the viability of protoscoleces. The main components were thymol (41.8%), carvacrol (28.8%), and p-cymene (8.4%). Findings showed that essential oil at the concentrations of 12.5 and 6.25 Î¼L/mL killed 100% protoscoleces after 5 and 20 minutes of exposure, respectively. In addition, thymol and carvacrol at the concentrations of 100 Î¼g/mL and 100 Î¼L/mL killed 100% protoscoleces after 10 minutes incubation, respectively. Obtained results in this investigation for the first time demonstrated that Z. multiflora essential oil and its main components might be a natural source for the production of new scolicidal agents.