This thesis describes the epidemiology of Motor Neurone Disease (MND) in Northern Ireland. A study of eye movements in MND is then described which had the aim of developing a biomarker for disease. The incidence of MND in Northern Ireland was found to be 2 per 100,000 person-years and, using capture-recapture analysis, was found to be an underestimate. The prevalence of MND in Northern Ireland was 4.9 per 100,000 population and remained unchanged due to the finding of 0.7 missing cases using capture-recapture analysis. The results of the epidemiological study described in this thesis added to current literature highlighting the likely level secular trend of MND. Incidence increased with age in males without peaking, a trend not observed since work performed in the Mayo Clinic, USA, in the 1980's. 'Timeliness of diagnosis' in MND was then examined revealing that the longest time period in the diagnostic process for patients with MND was that time spent with a physician before appropriate referral was made to a neurologist. It was felt that one of the reasons for this was that GPs were likely to be disillusioned with long waiting times for neurological outpatient referrals. Practical solutions are presented. A study of eye movements in MND was undertaken. The primary hypothesis stated that fixation would be abnormal in MND, particularly bulbar-onset disease. Fixation was indeed found to be abnormal in MND but did not relate to bulbar dysfunction. Instead fixation was found to correlate with the sub-clinical frontal lobe dysfunction that has been uncovered in patients with MND recently. To the authors knowledge this is the first study to examine fixation formally in a disease population. Furthermore, little is known of the neural substrate of fixation and this work helps in defining it.