Introduction: Fasciolosis is one of the most important parasitic disease common among both humans and livestock. That causes several health problems and economical losses in different parts of Iran. In order to control this disease, chemicals are used, which in some cases lead to resistance to the used substances and cause environmental problems.In this study, the effectiveness of the ethanolic extract of Lippia citriodora on the eggs of Fasciola hepatica is investigated.

  Methods: Fasciola hepatica eggs were obtained from the liver and gall bladders of naturally infected sheep and kept at 4˚C until use. Ethanol extract of Lippia citriodora kunth was provided from dried leaves. The eggs were exposed to Different concentration of extract   Concentrations of Lippia citriodora extract (10, 20, 30, 40, 50, 75 and 100%). Control group eggs were placed in chlorine-free water. Egg and embryo development stages to complete and release miracidia were examined every day.  Ethical considerations: This study was conducted after receiving the code of ethics (93-175-13) from the University Research Council.  Result: In concentration of 10 percent Lippia citriodora, miracidia was formed after 16 days in the egg. With increasing of concentration percentage of the extract, time of miracidia formation in eggs also rose. The time of miracidia formation between cases and control group is significantly different (Pvalue<0.05).  Conclusion: Our study shows that extract of Lippia citriodora is an effective inhibiting factor against development of Fasciola eggs.