The authors reported a case of niclofolan intoxication occurred during the trial of clonorchiasis treatment. The case, a 15 years old Korean schoolboy, took niclofolan(Bilevon) of total 473 mg(11 mg/kg) in 11 divided doses during 20 days. And the case suffered from neurologic symptoms such as severe headache, dizziness, nausea, vomiting, blurred vision, papilledema, retinal hemorrhage, an epsiode of seizure attack and elevated intracranial pressure, and hepatotoxic symptoms such as hepatomegaly, increased serum transaminases, and shoulder pain, excessive sweating and weight loss. Therapy was concentrated to the management of the elevated intracranial pressure. Hepatotoxic manifestations subsided within one month. The clinical signs related to elevated intracranial pressure persisted two months. Body weight regained after 2 months. And the symptoms of headache, dizziness and vomiting were complained intermittently until 4 months after onset. However, no subsequent clinical problems related with this episode has been noted until this record.