Levamisole is an anthelmintic agent and also immunostimulant drug which is used to treat colorectal cancer. The present study aimed to show accidental consumption of levamisole alone induced multifocal inflammatory leukoencephalopathy. A 53-year-old male was admitted to the Neurology Department of Farabi Hospital (Kermanshah, Iran) with walking inability and recognition disorder. Following clinical examinations, the patient diagnosed as multifocal inflammatory leukoencephalopathy following levamisole consumption.The patient was treated with intravenous methylprednisolone followed by prednisolone. The magnetic resonance imaging (MRI) was done 1 month later and did not show a reduction or remission in the lesions. History of the patient showed that he had accidentally consumed levamisole 8 months ago. It seems that the consumption of levamisole can induce multifocal inflammatory leukoencephalopathy and delayed treatment of the patient with corticosteroid cannot diminish the neurotoxicity of levamisole. In addition, the cytotoxic dose of levamisole induces irreversible multifocal inflammatory leukoencephalopathy.