Conversion disorder is characterized by the loss of one or several neurological functions, with no apparent organic cause. With this etiology, vision may be compromised in up to 5% of the patients in ophthalmologic emergencies. Hypnosis is a suggestion technique that has been used for years in the treatment of conversion disorder with positive results. Reported here is the case of a patient with color blindness whose evolution was satisfactory after 24 hours of one hypnosis session.