In a recent study, the fasciolicidal activity of Mirazid (a myrrh-derived drug) and its effect on the function and histopathology of host liver were investigated in Egyptian sheep, with triclabendazole (TCBZ) used as the positive control. Sheep were infected with metacercariae (150/animal) and treated 3 months later, either with Mirazid (10 mg/kg/day for six consecutive days) or TCBZ (a single dose of 10 mg/kg), or left untreated, as controls. When the animals were killed 4 weeks after the end of treatment, no Fasciola flukes or eggs could be found in the animals given TCBZ but the number of flukes found in the Mirazid-treated animals was only 6% lower than that recorded in the untreated sheep (a statistically insignificant difference). In terms of their Fasciola egg loads, serum concentrations of hepatic enzymes and hepatic histopathological changes, the Mirazid-treated sheep appeared very similar to the untreated, infected animals. The TCBZ-treated animals, in contrast, showed remarkably little evidence of hepatic pathology. It therefore appears that, in the treatment of ovine fascioliasis, at least some batches of Mirazid have little, if any, value.