A benzimidazole derivative with anthelminthic property. Although the mechanism of action has not been fully elucidated, thiabendazole inhibits the helminth-specific mitochondrial enzyme fumarate reductase, thereby inhibiting the citric acid cycle, mitochondrial respiration and subsequent production of ATP, ultimately leading to helminth's death. In addition, it has been suggested that thiabendazole may lead to inhibition of microtubule polymerization by binding to beta-tubulin and has an overt ovicidal effect with regard to some trichostrongylids.