Objective:To evaluate the effects of Mirazid and myrrh volatile oil on adult Fasciola gigantica(F.gigantica) under laboratory conditions.Methods:The effects of oleoresin extract of myrrh(Mirazid) and myrrh volatile oil on the surface morphology of adult F.gigantica following treatment in vitro had been determined by scanning electron microscopy.The results were compared with those observed in the fluke tegument following incubation in triclabendazole sulphoxide(TCBZ-SO),active form.(Fasinex,Ciba-Geigy).Results:Observations of the efficacy of Mirazid oleoresin extract and myrrh volatile oil indicated that both products showed dosedependent anthelmintic efficacy.The anterior half of the fluke was consistently more severely affected than the posterior half.The surface changes induced by Mirazid oleoresin extract were less severe than those observed after exposure to either myrrh volatile oil or TCBZ-SO.Flukes showed swelling after these treatments,but its level and blebbing were much greater with myrrh volatile oil;in which patches of tegumental sloughing were observed in the apical cone and the posterior mid-body region of flukes.This was not observed after treatment with Mirazid oleoresin extract.Conclusions:The comparatively more disruption,observed in myrrh volatile oil exposed specimens,compared to that exposed to Mirazid oleoresin extract might suggest that the anthelmintic activity of Mirazid oleo resin extract was attributed to its content of volatile oil.So,increasing the concentration of myrrh volatile oil in Mirazid might possibly help to developing its anthelmintic activity._______________________________________________ Objective: To evaluate the effects of Mirazid and myrrh volatile oil on adult Fasciola gigantica (F. gigantica) under laboratory conditions. Methods: The effects of oleoresin extract of myrrh (Mirazid) and myrrh volatile oil on the surface morphology of adult F. gigantica following treatment in vitro had been determined by scanning electron microscopy. the results were compared with those observed in the fluke tegument following incubation in triclabendazole sulphoxide (TCBZ-SO), active form. (Fasinex, Ciba-Geigy). Results: Observations of the efficacy of Mirazid oleoresin extract and myrrh volatile oil that that both both products showed dose dependent anthelmintic efficacy.The anterior half of the fluke was consistently more severely affected than the posterior half the. The surface changes induced by Mirazid oleoresin extract were less severe than those observed after exposure to either myrrh volatile oil or TCBZ-SO. Flukes showed swelling after these treatments, but its level and blebbing were much grea ter with myrrh volatile oil; in which patches of tegumental sloughing were observed in the apical cone and the posterior mid-body region of flukes. This was not observed after treatment with Mirazid oleoresin extract. Conclusions: The comparatively more disruption, observed in myrrh volatile oil exposed specimens, compared to that exposed to the Mirazid oleoresin extract may suggest that the anthelmintic activity of Mirazid oleo resin extract was attributed to its content of volatile oil. So, increasing the concentration of myrrh volatile oil in Mirazid might possibly help to develop its anthelmintic activity ._______________________________________________