Eosinophilia is 1 of the most common signs of fascioliasis especially during acute stage. In this study, our aim was to determine eosinophil cationic protein (ECP) in the sera of patients with fascioliasis and to investigate the likely relation between ECP and symptoms and signs of fascioliasis. Presence of high liver enzyme levels, eosinophilia, abdominal pain or urticaria was not found to be significantly associated with ECP positivity (p > 0.05), but statistical analyses revealed that ECP positivity was significantly related to weight loss status of patients (p < 0.005). In conclusion, ECP may be 1 of the likely causes of the symptoms and signs of fascioliasis.