In Crohn's disease, neurologic complications such as cerebrovascular accident, headache, peripheral neuropathy have been reported sporadically. The pathogenesis of these neurologic complications is still unknown and controversial. We experienced a 22-year-old man, with Crohn's disease accompanied by optic neuritis. Loss of visual acuity was developed during the worsening course of enterocutaneous fistula. After high dose steroid treatment, his visual acuity and neurologic symptoms improved immediately.