A national group of neurologists and ophthalmologists have evaluated guidelines and recommendations for diagnosis, treatment and follow up of optic neuritis based on clinical experience and a review of relevant literature. Optic neuritis is a common, well characterised condition that appears as an isolated syndrome or as a manifestation of multiple sclerosis. Several other diseases must be considered for a differential diagnosis. Corticosteroid treatment of optic neuritis has been investigated in a number of trials, which show that corticosteroid treatment speeds up the recovery of vision without affecting the final visual outcome. The diagnostic procedure and the treatment options have changed over the last few years. Some aspects of investigation, treatment and follow up are still controversial.