A 50-year-old woman presented with a 4-day history of apathy, perseveration, and confusion. These symptoms appeared 16 days after she had started taking sulfasalazine for rheumatoid arthritis. Brain MRI showed bilateral symmetrical discoid lesions involving the corona radiata. She fully recovered 7?days after stopping the medications. Follow-up brain MRI revealed remarkable improvement of the lesions. The pathomechanisms related to sulfasalazine- induced leukoencephalopathy may be demyelinating processes due to impaired T-cell-mediated immunity.